// src/modes/canvas/read_only.rs

use crate::config::binds::config::Config;
use crate::config::binds::key_sequences::KeySequenceTracker;
use crate::services::grpc_client::GrpcClient;
use crate::state::canvas_state::CanvasState; // Import the trait
use crate::state::pages::auth::AuthState;
use crate::state::pages::form::FormState;
use crossterm::event::KeyEvent;

#[derive(PartialEq)]
enum CharType {
    Whitespace,
    Alphanumeric,
    Punctuation,
}

pub async fn handle_read_only_event(
    app_state: &crate::state::state::AppState,
    key: KeyEvent,
    config: &Config,
    form_state: &mut FormState, // Keep specific types here for routing
    auth_state: &mut AuthState, // Keep specific types here for routing
    key_sequence_tracker: &mut KeySequenceTracker,
    current_position: &mut u64, // Needed for form actions
    total_count: u64,           // Needed for form actions
    grpc_client: &mut GrpcClient, // Needed for form actions
    command_message: &mut String,
    edit_mode_cooldown: &mut bool,
    ideal_cursor_column: &mut usize,
) -> Result<(bool, String), Box<dyn std::error::Error>> {
    // Check for entering Edit mode from Read-Only mode
    if config.is_enter_edit_mode_before(key.code, key.modifiers) {
        *edit_mode_cooldown = true;
        *command_message = "Entering Edit mode".to_string();
        // The actual mode switch happens in event.rs based on this return
        return Ok((false, command_message.clone()));
    }

    if config.is_enter_edit_mode_after(key.code, key.modifiers) {
        // Use the correct state based on context
        let (current_input, current_pos) = if app_state.ui.show_login {
            (
                auth_state.get_current_input(),
                auth_state.current_cursor_pos(),
            )
        } else {
            (
                form_state.get_current_input(),
                form_state.current_cursor_pos(),
            )
        };

        if !current_input.is_empty() && current_pos < current_input.len() {
            // Update the correct state
            if app_state.ui.show_login {
                auth_state.set_current_cursor_pos(current_pos + 1);
                *ideal_cursor_column = auth_state.current_cursor_pos();
            } else {
                form_state.set_current_cursor_pos(current_pos + 1);
                *ideal_cursor_column = form_state.current_cursor_pos();
            }
        }
        *edit_mode_cooldown = true;
        *command_message = "Entering Edit mode (after cursor)".to_string();
        // The actual mode switch happens in event.rs based on this return
        return Ok((false, command_message.clone()));
    }

    // Handle Read-Only mode keybindings
    if key.modifiers.is_empty() {
        key_sequence_tracker.add_key(key.code);
        let sequence = key_sequence_tracker.get_sequence();

        // Try to match the current sequence against Read-Only mode bindings
        if let Some(action) = config.matches_key_sequence_generalized(&sequence)
        {
            // Handle context-specific actions first
            let result = if app_state.ui.show_form
                && (action == "previous_entry" || action == "next_entry")
            {
                // Form-specific navigation
                crate::tui::functions::form::handle_action(
                    action,
                    form_state,
                    grpc_client,
                    current_position,
                    total_count,
                    ideal_cursor_column,
                )
                .await?
            } else if app_state.ui.show_login
                && (action == "move_up" || action == "move_down")
            {
                // Login-specific field navigation
                crate::tui::functions::login::handle_action(
                    action,
                    auth_state,
                    ideal_cursor_column,
                )
                .await?
            } else if app_state.ui.show_form
                && (action == "move_up" || action == "move_down")
            {
                // Form-specific field navigation (can reuse login handler logic if identical)
                 crate::tui::functions::form::handle_action(
                    action,
                    form_state,
                    grpc_client, // Might not be needed for simple up/down
                    current_position,
                    total_count,
                    ideal_cursor_column,
                )
                .await?
            } else {
                // Handle common navigation actions generically
                if app_state.ui.show_login {
                    execute_action(
                        action,
                        auth_state, // Pass AuthState
                        ideal_cursor_column,
                        key_sequence_tracker,
                        command_message,
                    )
                    .await?
                } else {
                    execute_action(
                        action,
                        form_state, // Pass FormState
                        ideal_cursor_column,
                        key_sequence_tracker,
                        command_message,
                    )
                    .await?
                }
            };
            key_sequence_tracker.reset();
            return Ok((false, result));
        }

        // Check if this might be a prefix of a longer sequence
        if config.is_key_sequence_prefix(&sequence) {
            return Ok((false, command_message.clone()));
        }

        // Since it's not part of a multi-key sequence, check for a direct action
        if sequence.len() == 1 && !config.is_key_sequence_prefix(&sequence) {
            if let Some(action) =
                config.get_read_only_action_for_key(key.code, key.modifiers)
            {
                // Handle context-specific actions first
                let result = if app_state.ui.show_form
                    && action == "previous_entry"
                {
                    // Form-specific navigation
                    crate::tui::functions::form::handle_action(
                        action,
                        form_state,
                        grpc_client,
                        current_position,
                        total_count,
                        ideal_cursor_column,
                    )
                    .await?
                } else {
                    // Handle common navigation actions generically
                    if app_state.ui.show_login {
                        execute_action(
                            action,
                            auth_state, // Pass AuthState
                            ideal_cursor_column,
                            key_sequence_tracker,
                            command_message,
                        )
                        .await?
                    } else {
                        execute_action(
                            action,
                            form_state, // Pass FormState
                            ideal_cursor_column,
                            key_sequence_tracker,
                            command_message,
                        )
                        .await?
                    }
                };
                key_sequence_tracker.reset();
                return Ok((false, result));
            }
        }
    } else {
        // If modifiers are pressed, check for direct key bindings
        key_sequence_tracker.reset();

        if let Some(action) =
            config.get_read_only_action_for_key(key.code, key.modifiers)
        {
            // Handle context-specific actions first
            let result = if app_state.ui.show_form
                && action == "previous_entry"
            {
                // Form-specific navigation
                crate::tui::functions::form::handle_action(
                    action,
                    form_state,
                    grpc_client,
                    current_position,
                    total_count,
                    ideal_cursor_column,
                )
                .await?
            } else {
                // Handle common navigation actions generically
                if app_state.ui.show_login {
                    execute_action(
                        action,
                        auth_state, // Pass AuthState
                        ideal_cursor_column,
                        key_sequence_tracker,
                        command_message,
                    )
                    .await?
                } else {
                    execute_action(
                        action,
                        form_state, // Pass FormState
                        ideal_cursor_column,
                        key_sequence_tracker,
                        command_message,
                    )
                    .await?
                }
            };
            return Ok((false, result));
        }
    }

    // Show a helpful message when no binding was found
    if !*edit_mode_cooldown {
        let default_key = "i".to_string();
        let edit_key = config
            .keybindings
            .read_only
            .get("enter_edit_mode_before")
            .and_then(|keys| keys.first())
            .unwrap_or(&default_key);
        *command_message = format!("Read-only mode - press {} to edit", edit_key);
    }

    Ok((false, command_message.clone()))
}

// Make this function generic over CanvasState
async fn execute_action<S: CanvasState>(
    action: &str,
    state: &mut S, // Use generic state
    ideal_cursor_column: &mut usize,
    key_sequence_tracker: &mut KeySequenceTracker, // Keep for resetting
    command_message: &mut String, // Keep for clearing
) -> Result<String, Box<dyn std::error::Error>> {
    match action {
        // These actions are handled outside now based on context
        "previous_entry" | "next_entry" => {
            key_sequence_tracker.reset();
            Ok(format!(
                "Action '{}' should be handled by context-specific logic",
                action
            ))
        }
        // These actions are handled outside now based on context
        "move_up" | "move_down" => {
            key_sequence_tracker.reset();
             Ok(format!(
                "Action '{}' should be handled by context-specific logic",
                action
            ))
        }
        "exit_edit_mode" => {
            // This action is primarily for Edit mode, but might be bound here too
            key_sequence_tracker.reset();
            command_message.clear();
            Ok("".to_string())
        }
        "move_left" => {
            let current_pos = state.current_cursor_pos();
            let new_pos = current_pos.saturating_sub(1);
            state.set_current_cursor_pos(new_pos); // Use trait setter
            *ideal_cursor_column = new_pos;
            Ok("".to_string())
        }
        "move_right" => {
            let current_input = state.get_current_input();
            let current_pos = state.current_cursor_pos();
            // In read-only, cursor stops AT the last character, not after
            if !current_input.is_empty()
                && current_pos < current_input.len().saturating_sub(1)
            {
                let new_pos = current_pos + 1;
                state.set_current_cursor_pos(new_pos); // Use trait setter
                *ideal_cursor_column = new_pos;
            }
            Ok("".to_string())
        }
        "move_word_next" => {
            let current_input = state.get_current_input();
            if !current_input.is_empty() {
                let new_pos =
                    find_next_word_start(current_input, state.current_cursor_pos());
                // Clamp to last valid character index in read-only
                let final_pos = new_pos.min(current_input.len().saturating_sub(1));
                state.set_current_cursor_pos(final_pos); // Use trait setter
                *ideal_cursor_column = final_pos;
            }
            Ok("".to_string())
        }
        "move_word_end" => {
            let current_input = state.get_current_input();
            if !current_input.is_empty() {
                let new_pos =
                    find_word_end(current_input, state.current_cursor_pos());
                // Clamp to last valid character index in read-only
                let final_pos = new_pos.min(current_input.len().saturating_sub(1));
                state.set_current_cursor_pos(final_pos); // Use trait setter
                *ideal_cursor_column = final_pos;
            }
            Ok("".to_string())
        }
        "move_word_prev" => {
            let current_input = state.get_current_input();
            if !current_input.is_empty() {
                let new_pos = find_prev_word_start(
                    current_input,
                    state.current_cursor_pos(),
                );
                state.set_current_cursor_pos(new_pos); // Use trait setter
                *ideal_cursor_column = new_pos;
            }
            Ok("".to_string())
        }
        "move_word_end_prev" => {
            let current_input = state.get_current_input();
            if !current_input.is_empty() {
                let new_pos = find_prev_word_end(
                    current_input,
                    state.current_cursor_pos(),
                );
                state.set_current_cursor_pos(new_pos); // Use trait setter
                *ideal_cursor_column = new_pos;
            }
            Ok("Moved to previous word end".to_string())
        }
        "move_line_start" => {
            state.set_current_cursor_pos(0); // Use trait setter
            *ideal_cursor_column = 0;
            Ok("".to_string())
        }
        "move_line_end" => {
            let current_input = state.get_current_input();
            if !current_input.is_empty() {
                let new_pos = current_input.len().saturating_sub(1);
                state.set_current_cursor_pos(new_pos); // Use trait setter
                *ideal_cursor_column = new_pos;
            } else {
                state.set_current_cursor_pos(0); // Handle empty input case
                *ideal_cursor_column = 0;
            }
            Ok("".to_string())
        }
        "move_first_line" => {
            // Field change is handled outside based on context
            // Just set cursor position based on ideal column
            let current_input = state.get_current_input();
            let max_cursor_pos = if !current_input.is_empty() {
                current_input.len().saturating_sub(1)
            } else {
                0
            };
            state.set_current_cursor_pos(
                (*ideal_cursor_column).min(max_cursor_pos),
            );
            Ok("Moved to first line".to_string()) // Message might be inaccurate now
        }
        "move_last_line" => {
            // Field change is handled outside based on context
            // Just set cursor position based on ideal column
            let current_input = state.get_current_input();
            let max_cursor_pos = if !current_input.is_empty() {
                current_input.len().saturating_sub(1)
            } else {
                0
            };
            state.set_current_cursor_pos(
                (*ideal_cursor_column).min(max_cursor_pos),
            );
            Ok("Moved to last line".to_string()) // Message might be inaccurate now
        }
        _ => Ok(format!("Unknown read-only action: {}", action)),
    }
}

// Helper functions remain unchanged as they operate on &str
fn get_char_type(c: char) -> CharType {
    if c.is_whitespace() {
        CharType::Whitespace
    } else if c.is_alphanumeric() {
        CharType::Alphanumeric
    } else {
        CharType::Punctuation
    }
}

fn find_next_word_start(text: &str, current_pos: usize) -> usize {
    let chars: Vec<char> = text.chars().collect();
    if chars.is_empty() || current_pos >= chars.len() {
        return current_pos;
    }

    let mut pos = current_pos;
    // Handle edge case where current_pos might be out of bounds after edits
    if pos >= chars.len() {
        return chars.len();
    }
    let initial_type = get_char_type(chars[pos]);

    // Move past characters of the same type
    while pos < chars.len() && get_char_type(chars[pos]) == initial_type {
        pos += 1;
    }

    // Move past whitespace
    while pos < chars.len() && get_char_type(chars[pos]) == CharType::Whitespace {
        pos += 1;
    }

    pos
}


fn find_word_end(text: &str, current_pos: usize) -> usize {
    let chars: Vec<char> = text.chars().collect();
    if chars.is_empty() {
        return 0;
    }
     // Handle edge case where current_pos might be out of bounds
    let mut pos = current_pos.min(chars.len().saturating_sub(1));

    // If starting on whitespace, move to the next non-whitespace
    if get_char_type(chars[pos]) == CharType::Whitespace {
         while pos + 1 < chars.len() && get_char_type(chars[pos + 1]) == CharType::Whitespace {
            pos += 1;
        }
        // If we are still on whitespace (meaning end of string or only whitespace left), return current pos
        if pos + 1 >= chars.len() || get_char_type(chars[pos + 1]) == CharType::Whitespace {
             return pos;
        }
        // Move to the start of the next word
        pos += 1;
    }

    // Now we are on a non-whitespace character
    let word_type = get_char_type(chars[pos]);
    while pos + 1 < chars.len() && get_char_type(chars[pos + 1]) == word_type {
        pos += 1;
    }

    pos
}


fn find_prev_word_start(text: &str, current_pos: usize) -> usize {
    let chars: Vec<char> = text.chars().collect();
    if chars.is_empty() || current_pos == 0 {
        return 0;
    }

    let mut pos = current_pos.saturating_sub(1);

    // Move past whitespace
    while pos > 0 && get_char_type(chars[pos]) == CharType::Whitespace {
        pos -= 1;
    }

    // Now on a non-whitespace or at the beginning
    if get_char_type(chars[pos]) != CharType::Whitespace {
        let word_type = get_char_type(chars[pos]);
        // Move to the beginning of the word
        while pos > 0 && get_char_type(chars[pos - 1]) == word_type {
            pos -= 1;
        }
    }

    // If pos is 0 and it's whitespace, keep it at 0. Otherwise, it's the start of the word.
    if pos == 0 && get_char_type(chars[pos]) == CharType::Whitespace {
        0
    } else {
        pos
    }
}


fn find_prev_word_end(text: &str, current_pos: usize) -> usize {
     let chars: Vec<char> = text.chars().collect();
    if chars.is_empty() || current_pos <= 1 { // Need at least 2 chars to find a *previous* word end
        return 0;
    }

    let mut pos = current_pos.saturating_sub(1); // Start looking one char back

    // Skip trailing whitespace from the current position
    while pos > 0 && get_char_type(chars[pos]) == CharType::Whitespace {
        pos -= 1;
    }

     // Now we are at the end of the word the cursor was in/after, or at the start
    if pos == 0 {
        return 0; // Reached the beginning
    }

    // Skip the word itself
    let word_type = get_char_type(chars[pos]);
     while pos > 0 && get_char_type(chars[pos - 1]) == word_type {
        pos -= 1;
    }

    // Skip whitespace before that word
    while pos > 0 && get_char_type(chars[pos - 1]) == CharType::Whitespace {
        pos -= 1;
    }

    // Now pos is at the beginning of the word *or* the end of the *previous* word.
    // If we moved back, pos-1 is the index we want.
    if pos > 0 {
        pos - 1
    } else {
        0 // We were at the first word
    }
}