// sprites.js - PNG image-based sprite system
// Uses pre-rendered assets from assets/ directory
// 16px native tile size, 3x scale for screen rendering

export const TILE = 16;
export const SCALE = 3;
export const TILE_PX = TILE * SCALE; // 48px on screen

// Also export as TILE_SIZE for backward compat
export const TILE_SIZE = TILE;

// ==================== Image cache ====================

const imageCache = {};
let assetsLoaded = false;
let onAssetsReady = null;

function loadImage(key, src) {
    return new Promise((resolve, reject) => {
        if (imageCache[key]) { resolve(imageCache[key]); return; }
        const img = new Image();
        img.onload = () => { imageCache[key] = img; resolve(img); };
        img.onerror = () => { console.warn(`[sprites] failed to load: ${src}`); resolve(null); };
        img.src = src;
    });
}

export function getImage(key) {
    return imageCache[key] || null;
}

/**
 * Preload all game assets. Returns a promise that resolves when done.
 */
export async function preloadAssets() {
    if (assetsLoaded) return;

    const loads = [];

    // Resolve asset base path relative to the HTML document
    const base = new URL('.', document.baseURI).href;

    // Map backgrounds
    loads.push(loadImage('map:lab', `${base}assets/map/lab.png`));
    loads.push(loadImage('map:pallet-town', `${base}assets/map/pallet-town.png`));
    loads.push(loadImage('map:house-a-1f', `${base}assets/map/house-a-1f.png`));
    loads.push(loadImage('map:route-1', `${base}assets/map/route-1.png`));

    // Character sprites (32x32 each)
    const dirs = ['front', 'back', 'left', 'right'];
    const frames = ['still', 'walk-1', 'walk-2'];
    for (const dir of dirs) {
        for (const frame of frames) {
            const key = `char:${dir}-${frame}`;
            loads.push(loadImage(key, `${base}assets/character/${dir}-${frame}.png`));
        }
    }

    // NPC sprites (16x16 each)
    const npcDirs = ['down', 'up', 'left', 'right'];
    for (const d of npcDirs) {
        loads.push(loadImage(`npc:a-${d}`, `${base}assets/npcs/a-${d}.png`));
    }

    await Promise.all(loads);
    assetsLoaded = true;
    console.log('[sprites] all assets loaded');
}

// ==================== Direction mapping ====================

// Map game direction to character sprite prefix
const DIR_TO_SPRITE = {
    down: 'front',
    up: 'back',
    left: 'left',
    right: 'right'
};

// Map game direction to NPC sprite suffix
const DIR_TO_NPC = {
    down: 'down',
    up: 'up',
    left: 'left',
    right: 'right'
};

// ==================== Drawing functions ====================

/**
 * Draw a map background image
 * @param {CanvasRenderingContext2D} ctx
 * @param {string} mapImageKey - key in imageCache (e.g. 'map:lab')
 * @param {number} offsetX - pixel offset for camera
 * @param {number} offsetY - pixel offset for camera
 */
export function drawMapImage(ctx, mapImageKey, offsetX, offsetY) {
    const img = imageCache[mapImageKey];
    if (!img) return;
    // Draw scaled: native pixels * SCALE
    ctx.imageSmoothingEnabled = false;
    ctx.drawImage(img, offsetX, offsetY, img.width * SCALE, img.height * SCALE);
}

/**
 * Draw the player character
 * @param {CanvasRenderingContext2D} ctx
 * @param {number} screenX - top-left X on screen
 * @param {number} screenY - top-left Y on screen
 * @param {string} direction - 'up'|'down'|'left'|'right'
 * @param {number} walkFrame - 0=still, 1=walk-1, 2=walk-2
 */
export function drawPlayer(ctx, screenX, screenY, direction, walkFrame) {
    const spriteDir = DIR_TO_SPRITE[direction] || 'front';
    const frameName = walkFrame === 0 ? 'still' : walkFrame === 1 ? 'walk-1' : 'walk-2';
    const key = `char:${spriteDir}-${frameName}`;
    const img = imageCache[key];
    if (!img) {
        // Fallback: colored rectangle
        ctx.fillStyle = '#00e599';
        ctx.fillRect(screenX, screenY, TILE_PX, TILE_PX * 2);
        return;
    }
    ctx.imageSmoothingEnabled = false;
    // Character is 32x32 native but represents a 1-tile-wide, 2-tile-tall entity
    // Draw at TILE_PX wide x TILE_PX tall (square, matching NPC size on grid)
    ctx.drawImage(img, screenX, screenY, TILE_PX, TILE_PX);
}

/**
 * Draw an NPC
 * @param {CanvasRenderingContext2D} ctx
 * @param {number} screenX - top-left X on screen
 * @param {number} screenY - top-left Y on screen
 * @param {string} facing - 'up'|'down'|'left'|'right'
 */
export function drawNPC(ctx, screenX, screenY, facing) {
    const dir = DIR_TO_NPC[facing] || 'down';
    const key = `npc:a-${dir}`;
    const img = imageCache[key];
    if (!img) {
        // Fallback
        ctx.fillStyle = '#ff44aa';
        ctx.fillRect(screenX, screenY, TILE_PX, TILE_PX);
        return;
    }
    ctx.imageSmoothingEnabled = false;
    // NPC is 16x16 native = 1 tile
    ctx.drawImage(img, screenX, screenY, TILE_PX, TILE_PX);
}

/**
 * Draw the interaction prompt (E button hint) above a tile
 */
export function drawInteractionPrompt(ctx, screenX, screenY) {
    const cx = screenX + TILE_PX / 2;
    const cy = screenY - 12;

    // Bubble background
    ctx.fillStyle = 'rgba(0, 0, 0, 0.7)';
    ctx.beginPath();
    ctx.roundRect(cx - 18, cy - 12, 36, 22, 6);
    ctx.fill();

    // Border
    ctx.strokeStyle = '#00e599';
    ctx.lineWidth = 1.5;
    ctx.beginPath();
    ctx.roundRect(cx - 18, cy - 12, 36, 22, 6);
    ctx.stroke();

    // Text
    ctx.fillStyle = '#ffffff';
    ctx.font = 'bold 12px "Segoe UI", system-ui, sans-serif';
    ctx.textAlign = 'center';
    ctx.textBaseline = 'middle';
    ctx.fillText('[E]', cx, cy);
}

/**
 * Draw the dialog box at the bottom of the screen
 */
export function drawDialogBox(ctx, canvasW, canvasH, text, speakerName) {
    const boxH = 100;
    const boxY = canvasH - boxH - 16;
    const boxX = 32;
    const boxW = canvasW - 64;

    // Background
    ctx.fillStyle = 'rgba(10, 14, 39, 0.92)';
    ctx.beginPath();
    ctx.roundRect(boxX, boxY, boxW, boxH, 10);
    ctx.fill();

    // Border
    ctx.strokeStyle = '#00e599';
    ctx.lineWidth = 2;
    ctx.beginPath();
    ctx.roundRect(boxX, boxY, boxW, boxH, 10);
    ctx.stroke();

    // Speaker name
    if (speakerName) {
        ctx.fillStyle = '#00e599';
        ctx.font = 'bold 14px "Segoe UI", system-ui, sans-serif';
        ctx.textAlign = 'left';
        ctx.textBaseline = 'top';
        ctx.fillText(speakerName, boxX + 16, boxY + 12);
    }

    // Text
    ctx.fillStyle = '#ffffff';
    ctx.font = '14px "Segoe UI", system-ui, sans-serif';
    ctx.textAlign = 'left';
    ctx.textBaseline = 'top';
    const textY = speakerName ? boxY + 34 : boxY + 16;
    // Simple word wrap
    wrapText(ctx, text, boxX + 16, textY, boxW - 32, 20);

    // Continue prompt
    ctx.fillStyle = '#555';
    ctx.font = '11px "Segoe UI", system-ui, sans-serif';
    ctx.textAlign = 'right';
    ctx.fillText('Press E to continue ▶', boxX + boxW - 16, boxY + boxH - 16);
}

function wrapText(ctx, text, x, y, maxWidth, lineHeight) {
    const words = text.split(' ');
    let line = '';
    let currentY = y;
    for (const word of words) {
        const test = line + (line ? ' ' : '') + word;
        if (ctx.measureText(test).width > maxWidth && line) {
            ctx.fillText(line, x, currentY);
            line = word;
            currentY += lineHeight;
        } else {
            line = test;
        }
    }
    if (line) ctx.fillText(line, x, currentY);
}