//! Tile visibility and data fetching utilities

use wasm_bindgen::JsCast;
use crate::camera::Camera;

/// Fetch tile data with caching
pub async fn fetch_cached(url: &str) -> Option<Vec<u8>> {
    let window = web_sys::window()?;
    let caches = window.caches().ok()?;
    let cache_name = "map-data-v5-sand";
    let cache = wasm_bindgen_futures::JsFuture::from(caches.open(cache_name)).await.ok()?;
    let cache: web_sys::Cache = cache.dyn_into().ok()?;

    let request = web_sys::Request::new_with_str(url).ok()?;
    let match_promise = cache.match_with_request(&request);
    let match_val = wasm_bindgen_futures::JsFuture::from(match_promise).await.ok()?;

    if !match_val.is_undefined() {
        let response: web_sys::Response = match_val.dyn_into().ok()?;
        let buffer_promise = response.array_buffer().ok()?;
        let buffer = wasm_bindgen_futures::JsFuture::from(buffer_promise).await.ok()?;
        let array = js_sys::Uint8Array::new(&buffer);
        return Some(array.to_vec());
    }

    // Network fetch
    let response_val = wasm_bindgen_futures::JsFuture::from(window.fetch_with_request(&request)).await.ok()?;
    let response: web_sys::Response = response_val.dyn_into().ok()?;
    
    // Clone response for cache
    let response_clone = response.clone().ok()?;
    let put_promise = cache.put_with_request(&request, &response_clone);
    wasm_bindgen_futures::JsFuture::from(put_promise).await.ok()?;

    let buffer_promise = response.array_buffer().ok()?;
    let buffer = wasm_bindgen_futures::JsFuture::from(buffer_promise).await.ok()?;
    let array = js_sys::Uint8Array::new(&buffer);
    Some(array.to_vec())
}

/// Get visible tiles based on current camera position
pub fn get_visible_tiles(camera: &Camera) -> Vec<(i32, i32, i32)> {
    // Select zoom level based on camera zoom
    // Zoom 6: World/Country view
    // Zoom 9: Region view
    // Zoom 12: City view
    // Zoom 14: Street view
    let z = if camera.zoom < 100.0 {
        2
    } else if camera.zoom < 500.0 {
        4
    } else if camera.zoom < 2000.0 {
        6
    } else if camera.zoom < 5000.0 {
        9
    } else if camera.zoom < 10000.0 {
        12
    } else {
        14
    };
    let n = 2.0f64.powi(z);
    
    let half_width = 1.0 * camera.aspect / camera.zoom;
    let half_height = 1.0 / camera.zoom;
    
    let min_x = (camera.x - half_width).max(0.0) as f64;
    let max_x = (camera.x + half_width).min(1.0) as f64;
    let min_y = (camera.y - half_height).max(0.0) as f64;
    let max_y = (camera.y + half_height).min(1.0) as f64;
    
    let min_tile_x = (min_x * n).floor() as i32;
    let max_tile_x = (max_x * n).floor() as i32;
    let min_tile_y = (min_y * n).floor() as i32;
    let max_tile_y = (max_y * n).floor() as i32;
    
    let mut tiles = Vec::new();
    for x in min_tile_x..=max_tile_x {
        for y in min_tile_y..=max_tile_y {
            tiles.push((z, x, y));
        }
    }
    tiles
}

/// Get parent tile for the tile retention hierarchy
pub fn get_parent_tile(z: i32, x: i32, y: i32) -> Option<(i32, i32, i32)> {
    // Hierarchy: 14 -> 12 -> 9 -> 6 -> 2
    let parent_z = match z {
        14 => 12,
        12 => 9,
        9 => 6,
        6 => 4,
        4 => 2,
        _ => return None,
    };
    
    // Calculate scale difference
    let diff = z - parent_z;
    let factor = 2i32.pow(diff as u32);
    
    Some((parent_z, x / factor, y / factor))
}