Source code: unstreaming for transaction send + warning message unification

diff --git a/src/constants.h b/src/constants.h
index cd4f88a..ad9aa0a 100644
--- a/src/constants.h
+++ b/src/constants.h
@@ -36,6 +36,16 @@
  */
 #define MAX_WALLET_NAME_LENGTH 64
 
+/**
+ * Maximum length of output index string
+ */
+#define MAX_OUTPUT_INDEX_LENGTH sizeof("101 of 203")
+
+/**
+ * Maximum number of external outputs handled simultaneously.
+ */
+#define MAX_EXT_OUTPUT_SIMPLIFIED_NUMBER 16
+
 /**
  * Maximum length (characters) of a base58check-encoded serialized extended pubkey.
  */
@@ -70,4 +80,4 @@
 
 #define MAX_STANDARD_P2WSH_STACK_ITEMS 100U
 #define MAX_STANDARD_P2WSH_SCRIPT_SIZE 3600U
-#define MAX_OPS_PER_SCRIPT             201U
\ No newline at end of file
+#define MAX_OPS_PER_SCRIPT             201U
diff --git a/src/handler/sign_psbt.c b/src/handler/sign_psbt.c
index d1bb90b..98083db 100644
--- a/src/handler/sign_psbt.c
+++ b/src/handler/sign_psbt.c
@@ -744,7 +744,7 @@ preprocess_inputs(dispatcher_context_t *dc,
             return false;
         } else if (is_internal == 0) {
             ++st->n_external_inputs;
-
+            st->warnings.external_inputs = true;
             PRINTF("INPUT %d is external\n", cur_input_index);
             continue;
         }
@@ -1214,12 +1214,11 @@ display_output(dispatcher_context_t *dc,
     }
 
     // Show address to the user
-    if (!ui_validate_output(dc,
-                            external_outputs_count,
-                            st->n_external_outputs,
-                            output_description,
-                            COIN_COINID_SHORT,
-                            out_amount)) {
+    if (!ui_transaction_streaming_validate_output(dc,
+                                                  external_outputs_count,
+                                                  st->n_external_outputs,
+                                                  output_description,
+                                                  out_amount)) {
         SEND_SW(dc, SW_DENY);
         return false;
     }
@@ -1342,21 +1341,21 @@ static bool __attribute__((noinline)) display_external_outputs(
 
 static bool __attribute__((noinline))
 display_warnings(dispatcher_context_t *dc, sign_psbt_state_t *st) {
-    // If there are external inputs, it is unsafe to sign, therefore we warn the user
-    if (st->n_external_inputs > 0 && !ui_warn_external_inputs(dc)) {
+    // If any input has non-default sighash, we warn the user
+    if (st->warnings.non_default_sighash && !ui_warn_nondefault_sighash(dc)) {
         SEND_SW(dc, SW_DENY);
         return false;
     }
 
-    // If any segwitv0 input is missing the non-witness-utxo, we warn the user and ask for
-    // confirmation
-    if (st->warnings.missing_nonwitnessutxo && !ui_warn_unverified_segwit_inputs(dc)) {
+    // If there are external inputs, it is unsafe to sign, therefore we warn the user
+    if (st->warnings.external_inputs && !ui_warn_external_inputs(dc)) {
         SEND_SW(dc, SW_DENY);
         return false;
     }
 
-    // If any input has non-default sighash, we warn the user
-    if (st->warnings.non_default_sighash && !ui_warn_nondefault_sighash(dc)) {
+    // If any segwitv0 input is missing the non-witness-utxo, we warn the user and ask for
+    // confirmation
+    if (st->warnings.missing_nonwitnessutxo && !ui_warn_unverified_segwit_inputs(dc)) {
         SEND_SW(dc, SW_DENY);
         return false;
     }
@@ -1383,37 +1382,49 @@ static bool __attribute__((noinline)) display_transaction(
     // if the value of fees is 10% or more of the amount, and it's more than 100000
     st->warnings.high_fee = 10 * fee >= st->inputs_total_amount && st->inputs_total_amount > 100000;
 
-    if (st->n_external_outputs == 0 || st->n_external_outputs == 1) {
-        // A simplified flow for most transactions: show everything in a single screen if there is
-        // exactly 0 (self-transfer) or 1 external output to show to the user
+    // Display warnings/risks information before the transaction title
+    // for the both classical and streaming cases.
+    if (!display_warnings(dc, st)) {
+        return false;
+    }
+
+    if (st->n_external_outputs <= MAX_EXT_OUTPUT_SIMPLIFIED_NUMBER) {
+        // A simplified flow for most transactions: show it using the classical review if there is
+        // exactly 0 (self-transfer) or <= MAX_EXT_OUTPUT_SIMPLIFIED_NUMBER external outputs to show
+        // to the user
 
         bool is_self_transfer = st->n_external_outputs == 0;
 
-        // show this output's address
-        char output_description[MAX_OUTPUT_SCRIPT_DESC_SIZE];
+        /** TRANSACTION CONFIRMATION */
+        /* Init*/
+        ui_transaction_simplified_init(st->is_wallet_default ? NULL : st->wallet_header.name,
+                                       is_self_transfer ? 1 : st->n_external_outputs,
+                                       st->warnings);
 
+        /* Adding outputs */
         if (!is_self_transfer) {
-            if (!format_script(st->outputs.output_scripts[0],
-                               st->outputs.output_script_lengths[0],
-                               output_description)) {
-                PRINTF("Invalid or unsupported script for external output\n");
-                SEND_SW(dc, SW_NOT_SUPPORTED);
-                return false;
+            for (unsigned int i = 0; i < st->n_external_outputs; i++) {
+                char output_description[MAX_OUTPUT_SCRIPT_DESC_SIZE];
+                /* It is possible to return the following error in the middle of
+                 * already shown screens of previous outputs
+                 */
+                if (!format_script(st->outputs.output_scripts[i],
+                                   st->outputs.output_script_lengths[i],
+                                   output_description)) {
+                    PRINTF("Invalid or unsupported script for external output\n");
+                    SEND_SW(dc, SW_NOT_SUPPORTED);
+                    return false;
+                }
+
+                ui_transaction_simplified_add(is_self_transfer ? 0 : st->outputs.output_amounts[i],
+                                              is_self_transfer ? NULL : output_description);
             }
+        } else {
+            ui_transaction_simplified_add(0, NULL);
         }
 
-        /** TRANSACTION CONFIRMATION
-         *
-         *  Show transaction amount, destination and fees, ask for final confirmation
-         */
-        if (!ui_validate_transaction_simplified(
-                dc,
-                COIN_COINID_SHORT,
-                st->is_wallet_default ? NULL : st->wallet_header.name,
-                is_self_transfer ? 0 : st->outputs.output_amounts[0],
-                is_self_transfer ? NULL : output_description,
-                st->warnings,
-                fee)) {
+        /* Start the review */
+        if (!ui_transaction_simplified_show(dc, fee)) {
             SEND_SW(dc, SW_DENY);
             return false;
         }
@@ -1421,20 +1432,15 @@ static bool __attribute__((noinline)) display_transaction(
         // Transactions with more than one external output; show one output per page,
         // using the streaming NBGL API.
 
-        // On NBGL devices, show the pre-approval screen
-        // "Review transaction to send Bitcoin"
-        if (!ui_transaction_prompt(dc)) {
-            SEND_SW(dc, SW_DENY);
-            return false;
-        }
-        // If it's not a default wallet policy, ask the user for confirmation, and abort if they
-        // deny
-        if (!st->is_wallet_default && !ui_authorize_wallet_spend(dc, st->wallet_header.name)) {
-            SEND_SW(dc, SW_DENY);
-            return false;
+        // If it's not a default wallet policy, let's save this info to ask the user for
+        // confirmation
+        if (!st->is_wallet_default) {
+            ui_prepare_authorize_wallet_spend(st->wallet_header.name);
         }
 
-        if (!display_warnings(dc, st)) {
+        // "Review transaction to send Bitcoin"
+        if (!ui_transaction_streaming_prompt(dc)) {
+            SEND_SW(dc, SW_DENY);
             return false;
         }
 
@@ -1444,17 +1450,12 @@ static bool __attribute__((noinline)) display_transaction(
          */
         if (!display_external_outputs(dc, st, internal_outputs)) return false;
 
-        if (st->warnings.high_fee && !ui_warn_high_fee(dc)) {
-            SEND_SW(dc, SW_DENY);
-            return false;
-        }
-
         /** TRANSACTION CONFIRMATION
          *
          *  Show summary info to the user (transaction fees), ask for final confirmation
          */
         // Show final user validation UI
-        if (!ui_validate_transaction(dc, COIN_COINID_SHORT, fee, false)) {
+        if (!ui_transaction_streaming_validate(dc, fee, st->warnings, false)) {
             SEND_SW(dc, SW_DENY);
             return false;
         }
diff --git a/src/handler/sign_psbt.h b/src/handler/sign_psbt.h
index 06f0f1d..7373b50 100644
--- a/src/handler/sign_psbt.h
+++ b/src/handler/sign_psbt.h
@@ -102,10 +102,10 @@ typedef struct signing_state_s {
     musig_signing_state_t musig;
 } signing_state_t;
 
-// We cache the first 2 external outputs; that's needed for the swap checks
-// Moreover, this helps the code for the simplified UX for transactions that
-// have a single external output.
-#define N_CACHED_EXTERNAL_OUTPUTS 2
+// We cache the first MAX_EXT_OUTPUT_SIMPLIFIED_NUMBER external outputs;
+// This is used by the code for the simplified UX for transactions;
+// Moreover, that is needed for the swap checks.
+#define N_CACHED_EXTERNAL_OUTPUTS MAX_EXT_OUTPUT_SIMPLIFIED_NUMBER
 
 typedef struct {
     uint32_t master_key_fingerprint;
diff --git a/src/ui/display.c b/src/ui/display.c
index 2fa75d9..29e3ece 100644
--- a/src/ui/display.c
+++ b/src/ui/display.c
@@ -238,17 +238,11 @@ bool ui_display_wallet_address(dispatcher_context_t *context,
     return io_ui_process(context);
 }
 
-bool ui_authorize_wallet_spend(dispatcher_context_t *context, const char *wallet_name) {
-    ui_wallet_state_t *state = (ui_wallet_state_t *) &g_ui_state;
-
-#ifdef HAVE_AUTOAPPROVE_FOR_PERF_TESTS
-    return true;
-#endif
-
-    strncpy(state->wallet_name, wallet_name, sizeof(state->wallet_name));
-    ui_display_spend_from_wallet_flow();
+void ui_prepare_authorize_wallet_spend(const char *wallet_name) {
+    ui_validate_transaction_state_t *state = (ui_validate_transaction_state_t *) &g_ui_state;
 
-    return io_ui_process(context);
+    strncpy(state->wallet_policy_name, wallet_name, sizeof(state->wallet_policy_name));
+    state->has_wallet_policy = true;
 }
 
 bool ui_warn_external_inputs(dispatcher_context_t *context) {
@@ -278,83 +272,62 @@ bool ui_warn_nondefault_sighash(dispatcher_context_t *context) {
     return io_ui_process(context);
 }
 
-bool ui_transaction_prompt(dispatcher_context_t *context) {
+bool ui_transaction_streaming_prompt(dispatcher_context_t *context) {
 #ifdef HAVE_AUTOAPPROVE_FOR_PERF_TESTS
     return true;
 #endif
 
-    ui_display_transaction_prompt();
+    ui_display_transaction_streaming_prompt();
     return io_ui_process(context);
 }
 
-bool ui_validate_output(dispatcher_context_t *context,
-                        int index,
-                        int total_count,
-                        const char *address_or_description,
-                        const char *coin_name,
-                        uint64_t amount) {
+bool ui_transaction_streaming_validate_output(dispatcher_context_t *context,
+                                              int index,
+                                              int total_count,
+                                              const char *address_or_description,
+                                              uint64_t amount) {
 #ifdef HAVE_AUTOAPPROVE_FOR_PERF_TESTS
     return true;
 #endif
 
-    ui_validate_output_state_t *state = (ui_validate_output_state_t *) &g_ui_state;
-
-    strncpy(state->address_or_description,
-            address_or_description,
-            sizeof(state->address_or_description));
-    format_sats_amount(coin_name, amount, state->amount);
-
-    if (total_count == 1) {
-        ui_display_output_address_amount_no_index_flow(index);
-    } else {
-        ui_display_output_address_amount_flow(index);
-    }
+    ui_validate_transaction_state_t *state = (ui_validate_transaction_state_t *) &g_ui_state;
 
-    return io_ui_process(context);
-}
+    format_output_index(index, total_count, state->output_index_str[0]);
 
-bool ui_warn_high_fee(dispatcher_context_t *context) {
-#ifdef HAVE_AUTOAPPROVE_FOR_PERF_TESTS
-    return true;
-#endif
+    strncpy(state->address_or_description[0],
+            address_or_description,
+            sizeof(state->address_or_description[0]));
+    format_sats_amount(COIN_COINID_SHORT, amount, state->amount[0]);
 
-    ui_warn_high_fee_flow();
+    ui_display_transaction_streaming_output_address_amount();
 
     return io_ui_process(context);
 }
 
-bool ui_validate_transaction(dispatcher_context_t *context,
-                             const char *coin_name,
-                             uint64_t fee,
-                             bool is_self_transfer) {
+bool ui_transaction_streaming_validate(dispatcher_context_t *context,
+                                       uint64_t fee,
+                                       tx_ux_warning_t warnings,
+                                       bool is_self_transfer) {
 #ifdef HAVE_AUTOAPPROVE_FOR_PERF_TESTS
     return true;
 #endif
 
     ui_validate_transaction_state_t *state = (ui_validate_transaction_state_t *) &g_ui_state;
 
-    format_sats_amount(coin_name, fee, state->fee);
+    format_sats_amount(COIN_COINID_SHORT, fee, state->fee);
+    state->warnings = warnings;
 
-    ui_accept_transaction_flow(is_self_transfer);
+    ui_display_transaction_streaming_flow(is_self_transfer);
 
     return io_ui_process(context);
 }
 
-bool ui_validate_transaction_simplified(dispatcher_context_t *context,
-                                        const char *coin_name,
-                                        const char *wallet_policy_name,
-                                        uint64_t amount,
-                                        const char *address_or_description,
-                                        tx_ux_warning_t warnings,
-                                        uint64_t fee) {
-#ifdef HAVE_AUTOAPPROVE_FOR_PERF_TESTS
-    return true;
-#endif
-
-    ui_validate_transaction_simplified_state_t *state =
-        (ui_validate_transaction_simplified_state_t *) &g_ui_state;
+void ui_transaction_simplified_init(const char *wallet_policy_name,
+                                    unsigned int outputs_num,
+                                    tx_ux_warning_t warnings) {
+    ui_validate_transaction_state_t *state = (ui_validate_transaction_state_t *) &g_ui_state;
 
-    memset(state, 0, sizeof(ui_validate_transaction_simplified_state_t));
+    memset(state, 0, sizeof(ui_validate_transaction_state_t));
 
     if (wallet_policy_name != NULL) {
         strncpy(state->wallet_policy_name, wallet_policy_name, sizeof(state->wallet_policy_name));
@@ -362,18 +335,40 @@ bool ui_validate_transaction_simplified(dispatcher_context_t *context,
     } else {
         memset(state->wallet_policy_name, 0, sizeof(state->wallet_policy_name));
     }
-    format_sats_amount(coin_name, amount, state->amount);
+    state->n_outputs = outputs_num;
+    state->warnings = warnings;
+
+    ui_display_transaction_simplified_flow_init();
+}
+
+void ui_transaction_simplified_add(uint64_t amount, const char *address_or_description) {
+    ui_validate_transaction_state_t *state = (ui_validate_transaction_state_t *) &g_ui_state;
+
+    format_sats_amount(COIN_COINID_SHORT, amount, state->amount[state->output_index]);
     if (address_or_description == NULL) {
         state->is_self_transfer = true;
     } else {
-        strncpy(state->address_or_description,
+        strncpy(state->address_or_description[state->output_index],
                 address_or_description,
-                sizeof(state->address_or_description));
+                sizeof(state->address_or_description[state->output_index]));
     }
-    state->warnings = warnings;
-    format_sats_amount(coin_name, fee, state->fee);
+    format_output_index(state->output_index + 1,
+                        state->n_outputs,
+                        state->output_index_str[state->output_index]);
+
+    ui_display_transaction_simplified_flow_add();
+    state->output_index++;
+}
+
+bool ui_transaction_simplified_show(dispatcher_context_t *context, uint64_t fee) {
+#ifdef HAVE_AUTOAPPROVE_FOR_PERF_TESTS
+    return true;
+#endif
+    ui_validate_transaction_state_t *state = (ui_validate_transaction_state_t *) &g_ui_state;
+
+    format_sats_amount(COIN_COINID_SHORT, fee, state->fee);
 
-    ui_accept_transaction_simplified_flow();
+    ui_display_transaction_simplified_flow_show();
 
     return io_ui_process(context);
 }
diff --git a/src/ui/display.h b/src/ui/display.h
index ab7f19e..e8b837d 100644
--- a/src/ui/display.h
+++ b/src/ui/display.h
@@ -22,14 +22,17 @@
 
 #if defined(TARGET_STAX) || defined(TARGET_FLEX)
 #define ICON_APP_IMPORTANT IMPORTANT_CIRCLE_ICON
+#define ICON_APP_WARNING   LARGE_WARNING_ICON
 #define ICON_APP_HOME      C_Bitcoin_64px
 #define ICON_APP_ACTION    C_Bitcoin_64px
 #elif defined(TARGET_APEX_P)
 #define ICON_APP_IMPORTANT IMPORTANT_CIRCLE_ICON
+#define ICON_APP_WARNING   LARGE_WARNING_ICON
 #define ICON_APP_HOME      C_Bitcoin_48px
 #define ICON_APP_ACTION    C_Bitcoin_48px
 #else
-#define ICON_APP_IMPORTANT C_icon_warning
+#define ICON_APP_IMPORTANT WARNING_ICON
+#define ICON_APP_WARNING   WARNING_ICON
 #define ICON_APP_HOME      C_bitcoin_logo
 #define ICON_APP_ACTION    C_bitcoin_logo_inv
 #endif
@@ -96,24 +99,18 @@ typedef struct {
 } ui_cosigner_pubkey_and_index_state_t;
 
 typedef struct {
-    char index[sizeof("output #999")];
-    char address_or_description[MAX(MAX_ADDRESS_LENGTH_STR + 1, MAX_OPRETURN_OUTPUT_DESC_SIZE)];
-    char amount[MAX_AMOUNT_LENGTH + 1];
-} ui_validate_output_state_t;
-
-typedef struct {
-    char fee[MAX_AMOUNT_LENGTH + 1];
-} ui_validate_transaction_state_t;
-
-typedef struct {
+    tx_ux_warning_t warnings;
     bool has_wallet_policy;
-    bool is_self_transfer;
     char wallet_policy_name[MAX_WALLET_NAME_LENGTH + 1];
-    char address_or_description[MAX(MAX_ADDRESS_LENGTH_STR + 1, MAX_OPRETURN_OUTPUT_DESC_SIZE)];
-    char amount[MAX_AMOUNT_LENGTH + 1];
+    bool is_self_transfer;
+    unsigned int n_outputs;
+    unsigned int output_index;
+    char output_index_str[MAX_EXT_OUTPUT_SIMPLIFIED_NUMBER][MAX_OUTPUT_INDEX_LENGTH + 1];
+    char address_or_description[MAX_EXT_OUTPUT_SIMPLIFIED_NUMBER]
+                               [MAX(MAX_ADDRESS_LENGTH_STR + 1, MAX_OPRETURN_OUTPUT_DESC_SIZE)];
+    char amount[MAX_EXT_OUTPUT_SIMPLIFIED_NUMBER][MAX_AMOUNT_LENGTH + 1];
     char fee[MAX_AMOUNT_LENGTH + 1];
-    tx_ux_warning_t warnings;
-} ui_validate_transaction_simplified_state_t;
+} ui_validate_transaction_state_t;
 
 /**
  * Union of all the states for each of the UI screens, in order to save memory.
@@ -124,10 +121,8 @@ typedef union {
     ui_path_and_message_state_t path_and_message;
     ui_wallet_state_t wallet;
     ui_cosigner_pubkey_and_index_state_t cosigner_pubkey_and_index;
-    ui_validate_output_state_t validate_output;
-    ui_validate_transaction_state_t validate_transaction;
     ui_register_wallet_policy_state_t register_wallet_policy;
-    ui_validate_transaction_simplified_state_t validate_transaction_simplified;
+    ui_validate_transaction_state_t validate_transaction_simplified;
 } ui_state_t;
 extern ui_state_t g_ui_state;
 
@@ -174,7 +169,7 @@ bool ui_display_wallet_address(dispatcher_context_t *context,
 
 bool ui_display_unusual_path(dispatcher_context_t *context, const char *bip32_path_str);
 
-bool ui_authorize_wallet_spend(dispatcher_context_t *context, const char *wallet_name);
+void ui_prepare_authorize_wallet_spend(const char *wallet_name);
 
 bool ui_warn_external_inputs(dispatcher_context_t *context);
 
@@ -182,30 +177,36 @@ bool ui_warn_unverified_segwit_inputs(dispatcher_context_t *context);
 
 bool ui_warn_nondefault_sighash(dispatcher_context_t *context);
 
-bool ui_validate_output(dispatcher_context_t *context,
-                        int index,
-                        int total_count,
-                        const char *address_or_description,
-                        const char *coin_name,
-                        uint64_t amount);
-
 bool ui_warn_high_fee(dispatcher_context_t *context);
 
-bool ui_validate_transaction(dispatcher_context_t *context,
-                             const char *coin_name,
-                             uint64_t fee,
-                             bool is_self_transfer);
-
-bool ui_validate_transaction_simplified(dispatcher_context_t *context,
-                                        const char *coin_name,
-                                        const char *wallet_policy_name,  // can be NULL
-                                        uint64_t amount,
-                                        const char *address_or_description,
-                                        tx_ux_warning_t warnings,
-                                        uint64_t fee);
+/* These 3 functions have to be called in following order:
+ * 1. init - to initialize the transaction signature flow with basic parameters.
+ * 2. add  - to add information for an output.
+ * 3. show - to actually start showing the transaction screens.
+ * These functions call respectively init, add and show functions from display_nbgl module.
+ */
+void ui_transaction_simplified_init(const char *wallet_policy_name,
+                                    unsigned int outputs_num,
+                                    tx_ux_warning_t warnings);
+void ui_transaction_simplified_add(uint64_t amount, const char *address_or_description);
+bool ui_transaction_simplified_show(dispatcher_context_t *context, uint64_t fee);
+
+bool ui_transaction_streaming_prompt(dispatcher_context_t *context);
+bool ui_transaction_streaming_validate_output(dispatcher_context_t *context,
+                                              int index,
+                                              int total_count,
+                                              const char *address_or_description,
+                                              uint64_t amount);
+bool ui_transaction_streaming_validate(dispatcher_context_t *context,
+                                       uint64_t fee,
+                                       tx_ux_warning_t warnings,
+                                       bool is_self_transfer);
 
 void set_ux_flow_response(bool approved);
 
+/* Functions from display_nbgl.c
+ * TODO: to merge display.c and display_nbgl.c
+ */
 void ui_display_pubkey_flow(void);
 
 void ui_display_pubkey_suspicious_flow(void);
@@ -228,18 +229,17 @@ void ui_display_unverified_segwit_inputs_flows(void);
 
 void ui_display_nondefault_sighash_flow(void);
 
-void ui_display_output_address_amount_flow(int index);
-
-void ui_display_output_address_amount_no_index_flow(int index);
-
 void ui_warn_high_fee_flow(void);
 
-void ui_accept_transaction_flow(bool is_self_transfer);
-
 void ui_display_register_wallet_policy_flow(void);
-void ui_accept_transaction_simplified_flow(void);
 
-void ui_display_transaction_prompt(void);
+void ui_display_transaction_simplified_flow_init(void);
+void ui_display_transaction_simplified_flow_add(void);
+void ui_display_transaction_simplified_flow_show(void);
+
+void ui_display_transaction_streaming_prompt(void);
+void ui_display_transaction_streaming_output_address_amount(void);
+void ui_display_transaction_streaming_flow(bool is_self_transfer);
 
 bool ui_post_processing_confirm_wallet_spend(dispatcher_context_t *context, bool success);
 
@@ -249,7 +249,6 @@ bool ui_post_processing_confirm_message(dispatcher_context_t *context, bool succ
 
 void ui_pre_processing_message(void);
 
-bool ui_transaction_prompt(dispatcher_context_t *context);
 void ui_display_post_processing_confirm_message(bool success);
 void ui_display_post_processing_confirm_transaction(bool success);
 void ui_set_display_prompt(void);
diff --git a/src/ui/display_nbgl.c b/src/ui/display_nbgl.c
index 7ddbba0..fd96453 100644
--- a/src/ui/display_nbgl.c
+++ b/src/ui/display_nbgl.c
@@ -24,15 +24,37 @@ const char GA_SIGN_MESSAGE[] = "Sign message";
 const char GA_REGISTER_ACCOUNT[] = "Register account";
 #endif /* #ifdef SCREEN_SIZE_WALLET */
 
-const char GA_UNVERIFIED_INPUTS[] = "Unverified inputs\nUpdate your wallet software";
+#ifdef SCREEN_SIZE_WALLET
+const char GA_SECURITY_RISK_TITLE[] = "Security risk detected";
+const char GA_WARN_HIGH_FEES_TITLE[] = "High fees warning";
+const char GA_RISK_EXTERNAL_INPUTS[] =
+    "This transaction has external inputs, and could spend more than you think.";
+const char GA_RISK_NON_STD_SIGHASH[] =
+    "This transaction uses non-standard signing rules (modified sighash), and could spend more "
+    "than you think.";
+const char GA_WARN_HIGH_FEES[] =
+    "You're about to review a transaction with fees above 10\% of the total amount.";
+
+#else
+const char GA_SECURITY_RISK_TITLE[] = "Security risk";
+const char GA_WARN_HIGH_FEES_TITLE[] = "High fees warning";
+const char GA_RISK_EXTERNAL_INPUTS[] = "There are external inputs\nReject if not sure";
+const char GA_RISK_NON_STD_SIGHASH[] = "Non-default sighash";
+const char GA_WARN_HIGH_FEES[] = "Fees are above 10%\n of total amount";
+#endif
+
+const char GA_BACK_TO_SAFETY[] = "Back to safety";
+const char GA_CONTINUE_ANYWAY[] = "Continue anyway";
+const char GA_RISK_UNVERIFIED_INPUTS[] = "Unverified inputs\nUpdate your wallet software";
 const char GA_REVIEW_TRANSACTION[] = "Review transaction\nto send Bitcoin";
 const char GA_REVIEW_MESSAGE[] = "Review message";
 const char GA_LOADING_TRANSACTION[] = "Loading transaction";
 const char GA_LOADING_MESSAGE[] = "Loading message";
 
-#define N_UX_PAIRS 18
+#define N_UX_PAIRS 51
 
 static nbgl_layoutTagValue_t pairs[N_UX_PAIRS];
+static unsigned int n_pairs;
 static nbgl_layoutTagValueList_t pairList;
 
 static nbgl_genericContents_t genericContent;
@@ -40,6 +62,8 @@ static nbgl_content_t contentList[4];
 
 extern bool G_was_processing_screen_shown;
 
+static void finish_transaction_flow(bool choice);
+
 // ux_flow_response
 static void ux_flow_response_false(void) {
     set_ux_flow_response(false);
@@ -128,108 +152,69 @@ static void generic_content_callback(int token, uint8_t index, int page) {
     }
 }
 
-static void finish_transaction_flow(bool choice) {
-    if (choice) {
-        nbgl_useCaseReviewStreamingFinish(GA_SIGN_TRANSACTION,
-                                          start_processing_transaction_callback);
-    } else {
-        status_transaction_cancel();
-    }
-}
-
-void ui_accept_transaction_flow(bool is_self_transfer) {
-    // Setup list
-    pairList.nbMaxLinesForValue = 0;
-    pairList.pairs = pairs;
-
-    if (!is_self_transfer) {
-        pairs[0].item = "Fees";
-        pairs[0].value = g_ui_state.validate_transaction.fee;
-
-        pairList.nbPairs = 1;
-    } else {
-        pairs[0].item = "Amount";
-        pairs[0].value = "Self-transfer";
-
-        pairs[1].item = "Fees";
-        pairs[1].value = g_ui_state.validate_transaction.fee;
-
-        pairList.nbPairs = 2;
-    }
-
-    nbgl_useCaseReviewStreamingContinue(&pairList, finish_transaction_flow);
-}
-
 #define COMBINE(a, b) a b
 
 // create the string "0 <coind_id> (self-transfer)"
 #define SELF_TRANSFER_DESCRIPTION COMBINE("0 ", COMBINE(COIN_COINID_SHORT, " (self-transfer)"))
 
-void ui_accept_transaction_simplified_flow(void) {
-    _Static_assert(N_UX_PAIRS >= 9, "Insufficient pairs for this flow");
-
+void ui_display_transaction_simplified_flow_init(void) {
+    /* 1 From + MAX_EXT_OUTPUT_SIMPLIFIED_NUMBER*3 + 1 Fees + 1 High fees */
+    _Static_assert(N_UX_PAIRS >= (1 + MAX_EXT_OUTPUT_SIMPLIFIED_NUMBER * 3 + 1 + 1),
+                   "Insufficient pairs for this flow");
     // Setup list
     pairList.nbMaxLinesForValue = 0;
     pairList.pairs = pairs;
+    n_pairs = 0;
 
-    int n_pairs = 0;
-
-    // Add warning screens for unverified inputs, external inputs or non-default sighash
-    if (g_ui_state.validate_transaction_simplified.warnings.missing_nonwitnessutxo) {
-        pairs[n_pairs++] = (nbgl_contentTagValue_t){.item = GA_UNVERIFIED_INPUTS,
-                                                    .value = "",
-                                                    .centeredInfo = true,
-                                                    .valueIcon = &ICON_APP_IMPORTANT};
-    }
-    if (g_ui_state.validate_transaction_simplified.warnings.external_inputs) {
-        pairs[n_pairs++] =
-            (nbgl_contentTagValue_t){.item = "There are external inputs\nReject if not sure",
-                                     .value = "",
-                                     .centeredInfo = true,
-                                     .valueIcon = &ICON_APP_IMPORTANT};
-    }
-    if (g_ui_state.validate_transaction_simplified.warnings.non_default_sighash) {
-        pairs[n_pairs++] =
-            (nbgl_contentTagValue_t){.item = "Non-default sighash\nReject if not sure",
-                                     .value = "",
-                                     .centeredInfo = true,
-                                     .valueIcon = &ICON_APP_IMPORTANT};
-    }
+    ui_validate_transaction_state_t *state = (ui_validate_transaction_state_t *) &g_ui_state;
 
-    if (g_ui_state.validate_transaction_simplified.has_wallet_policy) {
+    if (state->has_wallet_policy) {
         pairs[n_pairs++] = (nbgl_layoutTagValue_t){
             .item = "From",
-            .value = g_ui_state.validate_transaction_simplified.wallet_policy_name,
+            .value = state->wallet_policy_name,
         };
     }
+}
 
-    if (!g_ui_state.validate_transaction_simplified.is_self_transfer) {
-        pairs[n_pairs++] = (nbgl_layoutTagValue_t){
-            .item = "Amount",
-            .value = g_ui_state.validate_transaction_simplified.amount,
-        };
+void ui_display_transaction_simplified_flow_add(void) {
+    ui_validate_transaction_state_t *state = (ui_validate_transaction_state_t *) &g_ui_state;
+
+    unsigned int output_index = state->output_index;
+    if (!state->is_self_transfer) {
+        if (state->n_outputs > 1) {
+            pairs[n_pairs++] =
+                (nbgl_layoutTagValue_t){.item = "Transaction output",
+                                        .value = state->output_index_str[output_index],
+                                        .forcePageStart = true};
+        }
+        pairs[n_pairs++] = (nbgl_layoutTagValue_t){.item = "Amount",
+                                                   .value = state->amount[output_index],
+                                                   .forcePageStart = false};
 
         pairs[n_pairs++] = (nbgl_layoutTagValue_t){
             .item = "To",
-            .value = g_ui_state.validate_transaction_simplified.address_or_description,
+            .value = state->address_or_description[output_index],
         };
     } else {
         pairs[n_pairs++] =
             (nbgl_layoutTagValue_t){.item = "Amount", .value = SELF_TRANSFER_DESCRIPTION};
     }
+}
 
-    pairs[n_pairs++] = (nbgl_layoutTagValue_t){
-        .item = "Fees",
-        .value = g_ui_state.validate_transaction_simplified.fee,
-    };
+void ui_display_transaction_simplified_flow_show(void) {
+    ui_validate_transaction_state_t *state = (ui_validate_transaction_state_t *) &g_ui_state;
 
-    if (g_ui_state.validate_transaction_simplified.warnings.high_fee) {
-        pairs[n_pairs++] = (nbgl_contentTagValue_t){.item = "Fees are above 10%\n of total amount",
-                                                    .value = "",
+    if (state->warnings.high_fee) {
+        pairs[n_pairs++] = (nbgl_contentTagValue_t){.item = GA_WARN_HIGH_FEES_TITLE,
+                                                    .value = GA_WARN_HIGH_FEES,
                                                     .centeredInfo = true,
                                                     .valueIcon = &ICON_APP_IMPORTANT};
     }
 
+    pairs[n_pairs++] = (nbgl_layoutTagValue_t){.item = "Fees",
+                                               .value = state->fee,
+                                               .forcePageStart = state->n_outputs > 1 ? 1 : 0};
+
     pairList.nbPairs = n_pairs;
 
     nbgl_useCaseReview(TYPE_TRANSACTION,
@@ -241,28 +226,39 @@ void ui_accept_transaction_simplified_flow(void) {
                        start_transaction_callback);
 }
 
-void ui_display_transaction_prompt(void) {
+void ui_display_transaction_streaming_prompt(void) {
     nbgl_useCaseReviewStreamingStart(TYPE_TRANSACTION,
                                      &ICON_APP_ACTION,
                                      GA_REVIEW_TRANSACTION,
                                      NULL,
                                      start_transaction_callback);
+    ui_validate_transaction_state_t *state = (ui_validate_transaction_state_t *) &g_ui_state;
+
+    if (state->has_wallet_policy) {
+        pairs[0] = (nbgl_layoutTagValue_t){
+            .item = "From",
+            .value = state->wallet_policy_name,
+        };
+        // Setup list
+        pairList.nbMaxLinesForValue = 0;
+        pairList.nbPairs = 1;
+        pairList.pairs = pairs;
+
+        nbgl_useCaseReviewStreamingContinue(&pairList, start_transaction_callback);
+    }
 }
 
-void ui_display_output_address_amount_flow(int index) {
-    snprintf(g_ui_state.validate_output.index,
-             sizeof(g_ui_state.validate_output.index),
-             "#%d",
-             index);
+void ui_display_transaction_streaming_output_address_amount(void) {
+    ui_validate_transaction_state_t *state = (ui_validate_transaction_state_t *) &g_ui_state;
 
-    pairs[0].item = "Output";
-    pairs[0].value = g_ui_state.validate_output.index;
+    pairs[0].item = "Transaction output";
+    pairs[0].value = state->output_index_str[0];
 
     pairs[1].item = "Amount";
-    pairs[1].value = g_ui_state.validate_output.amount;
+    pairs[1].value = state->amount[0];
 
     pairs[2].item = "Address";
-    pairs[2].value = g_ui_state.validate_output.address_or_description;
+    pairs[2].value = state->address_or_description[0];
 
     // Setup list
     pairList.nbMaxLinesForValue = 0;
@@ -272,21 +268,46 @@ void ui_display_output_address_amount_flow(int index) {
     nbgl_useCaseReviewStreamingContinue(&pairList, start_transaction_callback);
 }
 
-void ui_display_output_address_amount_no_index_flow(int index) {
-    UNUSED(index);
-
-    pairs[0].item = "Amount";
-    pairs[0].value = g_ui_state.validate_output.amount;
-
-    pairs[1].item = "Address";
-    pairs[1].value = g_ui_state.validate_output.address_or_description;
-
+void ui_display_transaction_streaming_flow(bool is_self_transfer) {
     // Setup list
     pairList.nbMaxLinesForValue = 0;
-    pairList.nbPairs = 2;
     pairList.pairs = pairs;
 
-    nbgl_useCaseReviewStreamingContinue(&pairList, start_transaction_callback);
+    unsigned int l_n_pairs = 0;
+    ui_validate_transaction_state_t *state = (ui_validate_transaction_state_t *) &g_ui_state;
+
+    if (state->warnings.high_fee) {
+        pairs[l_n_pairs++] = (nbgl_contentTagValue_t){.item = GA_WARN_HIGH_FEES_TITLE,
+                                                      .value = GA_WARN_HIGH_FEES,
+                                                      .centeredInfo = true,
+                                                      .valueIcon = &ICON_APP_IMPORTANT};
+    }
+
+    if (!is_self_transfer) {
+        pairs[l_n_pairs].item = "Fees";
+        pairs[l_n_pairs++].value = state->fee;
+
+        pairList.nbPairs = l_n_pairs;
+    } else {
+        pairs[l_n_pairs].item = "Amount";
+        pairs[l_n_pairs++].value = "Self-transfer";
+
+        pairs[l_n_pairs].item = "Fees";
+        pairs[l_n_pairs++].value = state->fee;
+
+        pairList.nbPairs = l_n_pairs;
+    }
+
+    nbgl_useCaseReviewStreamingContinue(&pairList, finish_transaction_flow);
+}
+
+static void finish_transaction_flow(bool choice) {
+    if (choice) {
+        nbgl_useCaseReviewStreamingFinish(GA_SIGN_TRANSACTION,
+                                          start_processing_transaction_callback);
+    } else {
+        status_transaction_cancel();
+    }
 }
 
 // Continue light notify callback
@@ -339,7 +360,7 @@ void ui_display_register_wallet_policy_flow(void) {
     confirmed_status = "Account registered";
     rejected_status = "Account rejected";
 
-    int n_pairs = 0;
+    n_pairs = 0;
 
     pairList.nbMaxLinesForValue = 0;
     pairList.pairs = pairs;
@@ -535,28 +556,6 @@ void ui_set_display_prompt(void) {
     show_message_start_page = true;
 }
 
-void ui_display_spend_from_wallet_flow(void) {
-    confirmed_status = "Account name\nconfirmed";
-    rejected_status = "Account name rejected";
-
-    // Setup data to display
-    pairs[0].item = "Account name";
-    pairs[0].value = g_ui_state.wallet.wallet_name;
-
-    // Setup list
-    pairList.nbMaxLinesForValue = 0;
-    pairList.nbPairs = 1;
-    pairList.pairs = pairs;
-
-    nbgl_useCaseReviewLight(TYPE_OPERATION,
-                            &pairList,
-                            &ICON_APP_ACTION,
-                            "Spend from\nknown account",
-                            NULL,
-                            "Confirm account name",
-                            status_operation_callback);
-}
-
 // Address flow
 void ui_display_default_wallet_address_flow(void) {
     nbgl_useCaseAddressReview(g_ui_state.wallet.address,
@@ -567,41 +566,42 @@ void ui_display_default_wallet_address_flow(void) {
                               status_address_callback);
 }
 
-// Warning Flows
-void ui_warn_high_fee_flow(void) {
-    nbgl_useCaseChoice(&ICON_APP_IMPORTANT,
-                       "Warning",
-                       "Fees are above 10%\n of total amount",
-                       "Continue",
-                       "Reject",
+#ifdef SCREEN_SIZE_WALLET
+static void display_warning_generic_callback(bool confirm) {
+    if (!confirm) {
+        ux_flow_response_true();
+    } else {
+        status_transaction_cancel();
+    }
+}
+#endif /* #ifdef SCREEN_SIZE_WALLET */
+
+void ui_display_warning_generic(const char *msg) {
+    nbgl_useCaseChoice(&ICON_APP_WARNING,
+                       GA_SECURITY_RISK_TITLE,
+                       msg,
+#ifdef SCREEN_SIZE_WALLET
+                       GA_BACK_TO_SAFETY,
+                       GA_CONTINUE_ANYWAY,
+                       display_warning_generic_callback);
+#else
+                       GA_CONTINUE_ANYWAY,
+                       GA_BACK_TO_SAFETY,
                        start_transaction_callback);
+#endif /* #ifdef SCREEN_SIZE_WALLET */
 }
 
+// Warning/Security risks flows
 void ui_display_warning_external_inputs_flow(void) {
-    nbgl_useCaseChoice(&ICON_APP_IMPORTANT,
-                       "Warning",
-                       "There are external inputs",
-                       "Continue",
-                       "Reject if not sure",
-                       start_transaction_callback);
+    ui_display_warning_generic(GA_RISK_EXTERNAL_INPUTS);
 }
 
 void ui_display_unverified_segwit_inputs_flows(void) {
-    nbgl_useCaseChoice(&ICON_APP_IMPORTANT,
-                       "Warning",
-                       GA_UNVERIFIED_INPUTS,
-                       "Continue",
-                       "Reject if not sure",
-                       start_transaction_callback);
+    ui_display_warning_generic(GA_RISK_UNVERIFIED_INPUTS);
 }
 
 void ui_display_nondefault_sighash_flow(void) {
-    nbgl_useCaseChoice(&ICON_APP_IMPORTANT,
-                       "Warning",
-                       "Non-default sighash",
-                       "Continue",
-                       "Reject if not sure",
-                       start_transaction_callback);
+    ui_display_warning_generic(GA_RISK_NON_STD_SIGHASH);
 }
 
 // Statuses
diff --git a/src/ui/display_utils.c b/src/ui/display_utils.c
index de73157..b422153 100644
--- a/src/ui/display_utils.c
+++ b/src/ui/display_utils.c
@@ -46,3 +46,9 @@ void format_sats_amount(const char *coin_name,
              fractional_part ? fractional_str : "",
              coin_name);
 }
+
+void format_output_index(const unsigned int output_index,
+                         const unsigned int n_outputs,
+                         char out[static MAX_OUTPUT_INDEX_LENGTH + 1]) {
+    snprintf(out, MAX_OUTPUT_INDEX_LENGTH + 1, "%u of %u", output_index, n_outputs);
+}
diff --git a/src/ui/display_utils.h b/src/ui/display_utils.h
index c29a405..4beb3bf 100644
--- a/src/ui/display_utils.h
+++ b/src/ui/display_utils.h
@@ -20,4 +20,15 @@
  */
 void format_sats_amount(const char *coin_name,
                         uint64_t amount,
-                        char out[static MAX_AMOUNT_LENGTH + 1]);
\ No newline at end of file
+                        char out[static MAX_AMOUNT_LENGTH + 1]);
+
+/**
+ * Formats output index string ("101 of 203").
+ *
+ * @param output_index current output index
+ * @param n_outputs total number of outputs
+ * @param out the output array which must fit to MAX_OUTPUT_INDEX_LENGTH + 1 bytes length
+ */
+void format_output_index(const unsigned int output_index,
+                         const unsigned int n_outputs,
+                         char out[static MAX_OUTPUT_INDEX_LENGTH + 1]);