//! Settings persistence — saves/loads all app settings to JSON.
//!
//! **Purpose:** Persists tool settings, panel layout, and preferences between sessions.
//! Settings are saved to `~/.hcie/settings.json` and loaded on startup.

use serde::{Deserialize, Serialize};
use std::path::PathBuf;

/// A saved dock layout profile.
///
/// Stores a simplified pane layout description along with layout dimensions
/// so the user can save, load, rename, and delete dock configurations.
/// The full iced PaneGrid State cannot be serialized directly, so we store
/// the essential layout info: which panels are open and their relative positions.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DockProfile {
    pub name: String,
    /// List of panel names currently visible in the dock (e.g. "Layers", "History").
    pub visible_panels: Vec<String>,
    pub left_col1_w: f32,
    pub left_col2_w: f32,
    pub right_col1_w: f32,
    pub right_col2_w: f32,
    pub last_window_width: f32,
}

/// Main settings structure saved to disk.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AppSettings {
    /// Tool-specific settings.
    pub tool_settings: ToolSettings,
    /// Panel layout positions.
    pub panel_layout: PanelLayout,
    /// Window settings.
    pub window: WindowSettings,
    /// Saved dock layout profiles.
    #[serde(default)]
    pub dock_profiles: Vec<DockProfile>,
    /// Selected application color preset.
    #[serde(default)]
    pub theme_preset: crate::theme::ThemePreset,
}

/// Tool-specific settings that persist between sessions.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ToolSettings {
    pub brush_size: f32,
    pub brush_opacity: f32,
    pub brush_hardness: f32,
    pub brush_flow: f32,
    pub brush_spacing: f32,
    pub eraser_size: f32,
    pub eraser_opacity: f32,
    pub pen_size: f32,
    pub pen_opacity: f32,
    pub spray_radius: f32,
    pub spray_opacity: f32,
    pub gradient_opacity: f32,
    pub flood_fill_tolerance: f32,
    pub magic_wand_tolerance: f32,
    pub select_feather: f32,
    pub text_size: f32,
    pub vector_stroke_width: f32,
    pub vector_opacity: f32,
    /// Whether vector shapes are filled (true) or outlined only (false).
    #[serde(default = "default_vector_fill")]
    pub vector_fill: bool,
    /// Corner radius for VectorRect shapes.
    #[serde(default)]
    pub vector_radius: f32,
    /// Number of points for VectorStar shapes.
    #[serde(default = "default_vector_points")]
    pub vector_points: u32,
    /// Number of sides for VectorPolygon shapes.
    #[serde(default = "default_vector_sides")]
    pub vector_sides: u32,
    /// Spray particle size (size of each particle dot).
    #[serde(default = "default_spray_particle_size")]
    pub spray_particle_size: f32,
    /// Spray density (number of particles per dab).
    #[serde(default = "default_spray_density")]
    pub spray_density: u32,
    /// Gradient type: 0 = linear, 1 = radial.
    #[serde(default)]
    pub gradient_type: u32,
    /// Selection contiguous flag (magic wand / flood fill).
    #[serde(default = "default_contiguous")]
    pub selection_contiguous: bool,
    /// Anti-alias flag for selection tools.
    #[serde(default = "default_anti_alias")]
    pub selection_anti_alias: bool,
    /// Last font used by the Text tool.
    #[serde(default = "default_text_font")]
    pub text_font: String,
    /// Text angle in degrees.
    #[serde(default)]
    pub text_angle: f32,
    /// Whether the Text tool commits to a new layer each time.
    #[serde(default = "default_apply_to_new_layer")]
    pub tool_apply_to_new_layer: bool,
    pub last_active_tool: String,
}

fn default_vector_fill() -> bool {
    true
}
fn default_vector_points() -> u32 {
    5
}
fn default_vector_sides() -> u32 {
    6
}
fn default_spray_particle_size() -> f32 {
    4.0
}
fn default_spray_density() -> u32 {
    80
}
fn default_contiguous() -> bool {
    true
}
fn default_anti_alias() -> bool {
    true
}
fn default_text_font() -> String {
    "Arial".to_string()
}
fn default_apply_to_new_layer() -> bool {
    true
}

/// Panel layout positions and visibility.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PanelLayout {
    /// Left sidebar width in pixels.
    pub sidebar_width: f32,
    /// Whether the fixed toolbox sidebar shows labels as well as icons.
    #[serde(default)]
    pub sidebar_expanded: bool,
    /// Right tool settings panel width in pixels.
    pub tool_settings_width: f32,
    /// Which panels are visible.
    pub visible_panels: Vec<String>,
    /// Panel order in the dock.
    pub panel_order: Vec<String>,
}

/// Window settings.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct WindowSettings {
    pub width: f32,
    pub height: f32,
    pub maximized: bool,
}

impl Default for AppSettings {
    fn default() -> Self {
        Self {
            tool_settings: ToolSettings::default(),
            panel_layout: PanelLayout::default(),
            window: WindowSettings::default(),
            dock_profiles: Vec::new(),
            theme_preset: crate::theme::ThemePreset::default(),
        }
    }
}

impl Default for ToolSettings {
    fn default() -> Self {
        Self {
            brush_size: 20.0,
            brush_opacity: 1.0,
            brush_hardness: 0.8,
            brush_flow: 1.0,
            brush_spacing: 1.0,
            eraser_size: 20.0,
            eraser_opacity: 1.0,
            pen_size: 2.0,
            pen_opacity: 1.0,
            spray_radius: 40.0,
            spray_opacity: 0.5,
            gradient_opacity: 1.0,
            flood_fill_tolerance: 32.0,
            magic_wand_tolerance: 16.0,
            select_feather: 0.0,
            text_size: 24.0,
            vector_stroke_width: 1.0,
            vector_opacity: 1.0,
            vector_fill: true,
            vector_radius: 0.0,
            vector_points: 5,
            vector_sides: 6,
            spray_particle_size: 4.0,
            spray_density: 80,
            gradient_type: 0,
            selection_contiguous: true,
            selection_anti_alias: true,
            text_font: "Arial".to_string(),
            text_angle: 0.0,
            tool_apply_to_new_layer: true,
            last_active_tool: "Brush".to_string(),
        }
    }
}

impl Default for PanelLayout {
    fn default() -> Self {
        Self {
            sidebar_width: 36.0,
            sidebar_expanded: false,
            tool_settings_width: 200.0,
            visible_panels: vec![
                "Brushes & Tips".to_string(),
                "Color Palette".to_string(),
                "Layers".to_string(),
                "History".to_string(),
                "Filters".to_string(),
            ],
            panel_order: vec![
                "Brushes & Tips".to_string(),
                "Color Palette".to_string(),
                "Layers".to_string(),
                "History".to_string(),
                "Filters".to_string(),
            ],
        }
    }
}

impl Default for WindowSettings {
    fn default() -> Self {
        Self {
            width: 1280.0,
            height: 800.0,
            maximized: false,
        }
    }
}

impl AppSettings {
    /// Get the settings file path (~/.hcie/settings.json).
    pub fn file_path() -> PathBuf {
        let home = std::env::var("HOME").unwrap_or_else(|_| ".".to_string());
        PathBuf::from(home).join(".hcie").join("settings.json")
    }

    /// Load settings from disk, or return defaults if file doesn't exist.
    pub fn load() -> Self {
        let path = Self::file_path();
        if path.exists() {
            match std::fs::read_to_string(&path) {
                Ok(content) => match serde_json::from_str(&content) {
                    Ok(settings) => settings,
                    Err(e) => {
                        log::warn!("Failed to parse settings: {}, using defaults", e);
                        Self::default()
                    }
                },
                Err(e) => {
                    log::warn!("Failed to read settings: {}, using defaults", e);
                    Self::default()
                }
            }
        } else {
            Self::default()
        }
    }

    /// Save settings to disk.
    pub fn save(&self) -> Result<(), String> {
        let path = Self::file_path();

        // Create directory if it doesn't exist
        if let Some(parent) = path.parent() {
            std::fs::create_dir_all(parent)
                .map_err(|e| format!("Failed to create settings directory: {}", e))?;
        }

        let content = serde_json::to_string_pretty(self)
            .map_err(|e| format!("Failed to serialize settings: {}", e))?;

        std::fs::write(&path, content).map_err(|e| format!("Failed to write settings: {}", e))?;

        log::info!("Settings saved to {}", path.display());
        Ok(())
    }

    /// Reset all tool settings to defaults.
    pub fn reset_tool_defaults(&mut self) {
        self.tool_settings = ToolSettings::default();
    }

    /// Update tool settings from current ToolState.
    pub fn update_from_tool_state(&mut self, tool_state: &crate::app::ToolState) {
        self.tool_settings.brush_size = tool_state.brush_size;
        self.tool_settings.brush_opacity = tool_state.brush_opacity;
        self.tool_settings.brush_hardness = tool_state.brush_hardness;
        self.tool_settings.last_active_tool = format!("{:?}", tool_state.active_tool);
    }

    /// Apply saved settings to ToolState.
    pub fn apply_to_tool_state(&self, tool_state: &mut crate::app::ToolState) {
        tool_state.brush_size = self.tool_settings.brush_size;
        tool_state.brush_opacity = self.tool_settings.brush_opacity;
        tool_state.brush_hardness = self.tool_settings.brush_hardness;
    }
}

#[cfg(test)]
mod tests {
    use super::AppSettings;
    use crate::theme::ThemePreset;

    /// Proves settings written before Cycle 1 acquire safe theme and sidebar defaults.
    #[test]
    fn legacy_settings_default_new_cycle_one_fields() {
        let mut legacy = serde_json::to_value(AppSettings::default()).expect("serialize defaults");
        let object = legacy.as_object_mut().expect("settings object");
        object.remove("theme_preset");
        object
            .get_mut("panel_layout")
            .and_then(serde_json::Value::as_object_mut)
            .expect("panel layout object")
            .remove("sidebar_expanded");

        let settings: AppSettings =
            serde_json::from_value(legacy).expect("deserialize legacy settings");
        assert_eq!(settings.theme_preset, ThemePreset::Photopea);
        assert!(!settings.panel_layout.sidebar_expanded);
    }
}