import * as zlib from "zlib";

// Environment detection
const isNode = typeof Buffer !== 'undefined' && typeof process !== 'undefined' && process.versions?.node;

// Cross-platform type for binary data
type BinaryData = Buffer | Uint8Array;

// Cross-platform helper functions for reading integers
function readUInt8(data: BinaryData, offset: number): number {
	if (isNode && data instanceof Buffer) {
		return data.readUInt8(offset);
	}
	return (data as Uint8Array)[offset];
}

function readUInt16LE(data: BinaryData, offset: number): number {
	if (isNode && data instanceof Buffer) {
		return data.readUInt16LE(offset);
	}
	const bytes = data as Uint8Array;
	return bytes[offset] | (bytes[offset + 1] << 8);
}

function readUInt16BE(data: BinaryData, offset: number): number {
	if (isNode && data instanceof Buffer) {
		return data.readUInt16BE(offset);
	}
	const bytes = data as Uint8Array;
	return (bytes[offset] << 8) | bytes[offset + 1];
}

function readUInt32BE(data: BinaryData, offset: number): number {
	if (isNode && data instanceof Buffer) {
		return data.readUInt32BE(offset);
	}
	const bytes = data as Uint8Array;
	return (bytes[offset] << 24) | (bytes[offset + 1] << 16) | (bytes[offset + 2] << 8) | bytes[offset + 3];
}

function sliceData(data: BinaryData, start: number, end: number): BinaryData {
	return data.slice(start, end);
}

// Cross-platform decompression
async function inflateData(data: BinaryData): Promise<Buffer | Uint8Array> {
	if (isNode) {
		// Node.js environment - use promisified inflate
		const { promisify } = await import("util");
		const inflateAsync = promisify(zlib.inflate);
		return inflateAsync(data as Buffer);
	} else {
		// Browser environment - use sync version (it's actually async-friendly due to polyfill)
		const buffer = data instanceof Buffer ? data : Buffer.from(data);
		return zlib.inflateSync(buffer);
	}
}

/**
 * Convert RGB565 to RGB888 values using Factorio's exact method
 */
export function rgb565ToRgb888(rgb565Value: number): [number, number, number] {
	// This matches ByteColor(uint16_t rgb5) constructor in Factorio source
	const r = ((rgb565Value >> 11) & 0x1F) << 3;  // 5 bits -> 8 bits
	const g = ((rgb565Value >> 5) & 0x3F) << 2;   // 6 bits -> 8 bits  
	const b = (rgb565Value & 0x1F) << 3;          // 5 bits -> 8 bits
	return [r, g, b];
}

/**
 * Render chunk data to get RGB565 pixel array
 */
export async function renderChunkToPixels(chunkData: BinaryData): Promise<Uint16Array> {
	try {
		const decompressed = await inflateData(chunkData);
		const pixels = new Uint16Array(32 * 32);
		
		// Ensure we don't read beyond available data
		const maxPixels = Math.min(decompressed.length / 2, 32 * 32);
		
		for (let i = 0; i < maxPixels; i++) {
			pixels[i] = readUInt16LE(decompressed, i * 2);
		}
		
		// Fill remaining pixels with black (0) if we have less data than expected
		for (let i = maxPixels; i < 32 * 32; i++) {
			pixels[i] = 0;
		}
		
		return pixels;
	} catch (decompressError) {
		console.error(`Failed to decompress chunk data: ${decompressError}`);
		// Return black pixels on error
		return new Uint16Array(32 * 32);
	}
}

/**
 * Extract a 32x32 chunk area from a 256x256 tile
 */
export function extractChunkFromTile(tilePixels: Uint16Array, chunkX: number, chunkY: number): Uint16Array {
	const chunkPixels = new Uint16Array(32 * 32);
	
	for (let y = 0; y < 32; y++) {
		for (let x = 0; x < 32; x++) {
			const tileX = chunkX * 32 + x;
			const tileY = chunkY * 32 + y;
			const tileIndex = tileY * 256 + tileX;
			const chunkIndex = y * 32 + x;
			chunkPixels[chunkIndex] = tilePixels[tileIndex];
		}
	}
	
	return chunkPixels;
}

/**
 * Render tile data to RGB565 pixel array (256x256)
 * Supports rendering up to a specific tick for timelapse functionality
 */
export async function renderTileToPixels(tileData: BinaryData, maxTick?: number): Promise<Uint16Array> {
	const currentPixels = new Uint16Array(256 * 256); // 256x256 tile
	
	let offset = 0;
	while (offset < tileData.length) {
		if (offset + 1 > tileData.length) {
			break;
		}
		
		const type = readUInt8(tileData, offset);
		offset += 1;

		if (type === 1) { // Chunk
			if (offset + 7 > tileData.length) {
				break;
			}
			
			const tick = readUInt32BE(tileData, offset) * 60; // Convert back to actual tick
			offset += 4;
			
			// Skip this chunk if it's beyond our target tick
			if (maxTick !== undefined && tick > maxTick) {
				const chunkCoordsByte = readUInt8(tileData, offset);
				offset += 1;
				const length = readUInt16BE(tileData, offset);
				offset += 2;
				offset += length; // Skip chunk data
				continue;
			}
			
			const chunkCoordsByte = readUInt8(tileData, offset);
			offset += 1;
			const length = readUInt16BE(tileData, offset);
			offset += 2;

			if (offset + length > tileData.length) {
				break;
			}

			const chunkX = chunkCoordsByte >> 4;
			const chunkY = chunkCoordsByte & 0x0F;
			const chunkData = sliceData(tileData, offset, offset + length);

			try {
				const chunkPixels = await renderChunkToPixels(chunkData);
				
				// Update current pixel state
				for (let y = 0; y < 32; y++) {
					for (let x = 0; x < 32; x++) {
						const chunkIndex = y * 32 + x;
						const tileX = chunkX * 32 + x;
						const tileY = chunkY * 32 + y;
						const tileIndex = tileY * 256 + tileX;
						currentPixels[tileIndex] = chunkPixels[chunkIndex];
					}
				}
			} catch (decompressError) {
				console.error(`Failed to decompress chunk data: ${decompressError}`);
			}
			
			offset += length;
		} else if (type === 2) { // Pixels
			if (offset + 6 > tileData.length) {
				break;
			}
			
			const tick = readUInt32BE(tileData, offset) * 60; // Convert back to actual tick
			offset += 4;
			const pixelCount = readUInt16BE(tileData, offset);
			offset += 2;
			
			const expectedDataLength = pixelCount * 6;
			if (offset + expectedDataLength > tileData.length) {
				break;
			}
			
			// Skip this pixel changeset if it's beyond our target tick
			if (maxTick !== undefined && tick > maxTick) {
				offset += expectedDataLength;
				continue;
			}
			
			// Apply pixel changes to current state
			for (let i = 0; i < pixelCount; i++) {
				const pixelOffset = offset + i * 6;
				const x = readUInt8(tileData, pixelOffset);
				const y = readUInt8(tileData, pixelOffset + 1);
				const newColor = readUInt16BE(tileData, pixelOffset + 2);
				// oldColor at pixelOffset + 4 is not needed for rendering
				
				// Update current pixel state
				if (x < 256 && y < 256) {
					const tileIndex = y * 256 + x;
					currentPixels[tileIndex] = newColor;
				}
			}
			
			offset += expectedDataLength;
		} else {
			break;
		}
	}

	return currentPixels;
}

/**
 * Convert RGB565 pixel array to RGBA pixel data for canvas rendering
 * Returns Uint8ClampedArray that can be used to create ImageData in browser
 */
export function pixelsToRGBA(pixels: Uint16Array): Uint8ClampedArray {
	const imageData = new Uint8ClampedArray(256 * 256 * 4);
	
	for (let i = 0; i < 256 * 256; i++) {
		const rgb565Value = pixels[i];
		const [r, g, b] = rgb565ToRgb888(rgb565Value);
		const bufferIndex = i * 4;
		
		imageData[bufferIndex] = r;
		imageData[bufferIndex + 1] = g;
		imageData[bufferIndex + 2] = b;
		imageData[bufferIndex + 3] = 255; // Alpha
	}
	
	return imageData;
}

/**
 * Convert RGB565 pixel array to ImageData for canvas rendering (browser only)
 */
export function pixelsToImageData(pixels: Uint16Array): any {
	if (typeof (globalThis as any).ImageData === 'undefined') {
		throw new Error('ImageData is not available in this environment. Use pixelsToRGBA() instead.');
	}
	const rgbaData = pixelsToRGBA(pixels);
	return new (globalThis as any).ImageData(rgbaData, 256, 256);
}

/**
 * Parse tile data and extract all available ticks for timelapse functionality
 */
export function extractAvailableTicks(tileData: BinaryData): number[] {
	const ticks = new Set<number>();
	
	let offset = 0;
	while (offset < tileData.length) {
		if (offset + 1 > tileData.length) {
			break;
		}
		
		const type = readUInt8(tileData, offset);
		offset += 1;

		if (type === 1) { // Chunk
			if (offset + 7 > tileData.length) {
				break;
			}
			
			const tick = readUInt32BE(tileData, offset) * 60; // Convert back to actual tick
			ticks.add(tick);
			offset += 4;
			
			const chunkCoordsByte = readUInt8(tileData, offset);
			offset += 1;
			const length = readUInt16BE(tileData, offset);
			offset += 2;
			offset += length; // Skip chunk data
		} else if (type === 2) { // Pixels
			if (offset + 6 > tileData.length) {
				break;
			}
			
			const tick = readUInt32BE(tileData, offset) * 60; // Convert back to actual tick
			ticks.add(tick);
			offset += 4;
			
			const pixelCount = readUInt16BE(tileData, offset);
			offset += 2;
			
			const expectedDataLength = pixelCount * 6;
			if (offset + expectedDataLength > tileData.length) {
				break;
			}
			
			offset += expectedDataLength;
		} else {
			break;
		}
	}

	return Array.from(ticks).sort((a, b) => a - b);
}