"use strict";

import { readFileSync, statSync, existsSync } from "node:fs";
import { resolve, extname } from "node:path";

/** 支持的图片格式及其 MIME 类型 */
const IMAGE_MIME_TYPES: Record<string, string> = {
  png: "image/png",
  jpg: "image/jpeg",
  jpeg: "image/jpeg",
};

/** 支持的视频格式及其 MIME 类型 */
const VIDEO_MIME_TYPES: Record<string, string> = {
  mp4: "video/mp4",
  mov: "video/quicktime",
  m4v: "video/x-m4v",
  avi: "video/x-msvideo",
  webm: "video/webm",
  wmv: "video/x-ms-wmv",
};

export interface ImageUrlPart {
  type: "image_url";
  image_url: { url: string };
}

export interface VideoUrlPart {
  type: "video_url";
  video_url: { url: string };
}

export interface TextPart {
  type: "text";
  text: string;
}

export type ContentPart = ImageUrlPart | VideoUrlPart | TextPart;

/** 判断是否为 HTTP(S) URL */
export function isUrl(source: string): boolean {
  return source.startsWith("http://") || source.startsWith("https://");
}

/** 剥离 pi 的 @ 路径前缀 */
function stripAtPrefix(path: string): string {
  return path.startsWith("@") ? path.slice(1) : path;
}

/** 解析文件路径（相对 cwd + 去掉 @ 前缀） */
function resolvePath(rawPath: string, cwd: string): string {
  const cleaned = stripAtPrefix(rawPath);
  return resolve(cwd, cleaned);
}

/**
 * 处理图片源（本地文件或 URL），返回 API 所需的 ContentPart。
 * 本地文件会 base64 编码为 data URL。
 */
export function processImage(
  source: string,
  cwd: string,
  maxSizeMB: number
): ImageUrlPart {
  if (isUrl(source)) {
    return { type: "image_url", image_url: { url: source } };
  }

  const resolved = resolvePath(source, cwd);
  if (!existsSync(resolved)) {
    throw new Error(`Image file not found: ${resolved}`);
  }

  const stat = statSync(resolved);
  const sizeMB = stat.size / (1024 * 1024);
  if (sizeMB > maxSizeMB) {
    throw new Error(
      `Image file too large: ${sizeMB.toFixed(1)}MB (max ${maxSizeMB}MB): ${resolved}`
    );
  }

  const ext = extname(resolved).slice(1).toLowerCase();
  const mime = IMAGE_MIME_TYPES[ext];
  if (!mime) {
    throw new Error(
      `Unsupported image format: .${ext}. Supported: ${Object.keys(IMAGE_MIME_TYPES).join(", ")}`
    );
  }

  const data = readFileSync(resolved);
  const b64 = data.toString("base64");
  return {
    type: "image_url",
    image_url: { url: `data:${mime};base64,${b64}` },
  };
}

/**
 * 处理视频源（本地文件或 URL），返回 API 所需的 ContentPart。
 * 本地文件会 base64 编码为 data URL。
 */
export function processVideo(
  source: string,
  cwd: string,
  maxSizeMB: number
): VideoUrlPart {
  if (isUrl(source)) {
    return { type: "video_url", video_url: { url: source } };
  }

  const resolved = resolvePath(source, cwd);
  if (!existsSync(resolved)) {
    throw new Error(`Video file not found: ${resolved}`);
  }

  const stat = statSync(resolved);
  const sizeMB = stat.size / (1024 * 1024);
  if (sizeMB > maxSizeMB) {
    throw new Error(
      `Video file too large: ${sizeMB.toFixed(1)}MB (max ${maxSizeMB}MB): ${resolved}`
    );
  }

  const ext = extname(resolved).slice(1).toLowerCase();
  const mime = VIDEO_MIME_TYPES[ext];
  if (!mime) {
    throw new Error(
      `Unsupported video format: .${ext}. Supported: ${Object.keys(VIDEO_MIME_TYPES).join(", ")}`
    );
  }

  const data = readFileSync(resolved);
  const b64 = data.toString("base64");
  return {
    type: "video_url",
    video_url: { url: `data:${mime};base64,${b64}` },
  };
}