use std::path::Path;

use serde::{Deserialize, Serialize};
use thiserror::Error;

use crate::mirror::snapshot::BoardLayer;

#[derive(Debug, Error)]
pub enum SettingsError {
    #[error("io error: {0}")]
    Io(#[from] std::io::Error),
    #[error("json error: {0}")]
    Json(#[from] serde_json::Error),
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Settings {
    pub schema_version: u32,
    pub hide_stash_layer: BoardLayer,
    pub snapshot_ring_size: usize,
    pub snapshot_mem_budget_bytes: usize,
    pub poll_interval_ms: u64,
    #[serde(default = "default_track_non_active")]
    pub track_non_active_layers: bool,
    #[serde(default = "default_grid_mm")]
    pub grid_snap_x_mm: f64,
    #[serde(default = "default_grid_mm")]
    pub grid_snap_y_mm: f64,
    #[serde(default = "default_true_bool")]
    pub grid_snap_link_axes: bool,
    #[serde(default = "default_true_bool")]
    pub grid_snap_refill_zones: bool,
    pub ui: UiSettings,
    pub keybinds: KeybindSettings,
}

fn default_track_non_active() -> bool { true }
fn default_grid_mm() -> f64 { 0.254 }
fn default_true_bool() -> bool { true }

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct UiSettings {
    pub dark_mode: Option<bool>,
    pub preview_size_px: u32,
    pub show_item_counts: bool,
    pub show_icons: bool,
}

impl Default for UiSettings {
    fn default() -> Self {
        Self {
            dark_mode: None,
            preview_size_px: 192,
            show_item_counts: true,
            show_icons: true,
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize, Default)]
pub struct KeybindSettings {
    pub new_layer_from_selection: Option<String>,
}

impl Default for Settings {
    fn default() -> Self {
        Self {
            schema_version: 1,
            hide_stash_layer: BoardLayer::Eco2User,
            snapshot_ring_size: 50,
            snapshot_mem_budget_bytes: 256 * 1024 * 1024,
            poll_interval_ms: 100,
            track_non_active_layers: true,
            grid_snap_x_mm: 0.254,
            grid_snap_y_mm: 0.254,
            grid_snap_link_axes: true,
            grid_snap_refill_zones: true,
            ui: UiSettings::default(),
            keybinds: KeybindSettings::default(),
        }
    }
}

impl Settings {
    pub const SCHEMA_VERSION: u32 = 1;

    pub fn load_from(path: &Path) -> Result<Self, SettingsError> {
        let bytes = std::fs::read(path)?;
        Ok(serde_json::from_slice(&bytes)?)
    }

    pub fn save_to(&self, path: &Path) -> Result<(), SettingsError> {
        if let Some(parent) = path.parent() {
            std::fs::create_dir_all(parent)?;
        }
        let tmp = path.with_extension("json.tmp");
        let bytes = serde_json::to_vec_pretty(self)?;
        std::fs::write(&tmp, &bytes)?;
        std::fs::rename(&tmp, path)?;
        Ok(())
    }
}