const path = require("path");
const fs = require("fs");
const { execSync } = require("child_process");
const { DateTime } = require("luxon");

const getGitCreatedTime = (filePath) => {
  try {
    const result = execSync(
      `git log --diff-filter=A --follow --format=%aI -- "${filePath}" | tail -1`,
      { encoding: "utf-8", stdio: ["pipe", "pipe", "pipe"] }
    ).trim();
    if (result) {
      return DateTime.fromISO(result);
    }
  } catch (e) {
    // Git command failed, return null
  }
  return null;
};

const getGitModifiedTime = (filePath) => {
  try {
    const result = execSync(
      `git log -1 --format=%aI -- "${filePath}"`,
      { encoding: "utf-8", stdio: ["pipe", "pipe", "pipe"] }
    ).trim();
    if (result) {
      return DateTime.fromISO(result);
    }
  } catch (e) {
    // Git command failed, return null
  }
  return null;
};

const getTitleFromFilename = (filePath) => {
  const basename = path.basename(filePath, '.md');
  return basename
    .split('-')
    .map(word => word.charAt(0).toUpperCase() + word.slice(1))
    .join(' ');
}

const getFileCreatedTime = (filePath) => {
  try {
    const stats = fs.statSync(filePath);
    const time = stats.birthtime ?? stats.mtime;
    return DateTime.fromJSDate(time);
  } catch (e) {
    return null;
  }
}

const getFileModifiedTime = (filePath) => {
  try {
    const stats = fs.statSync(filePath);
    return DateTime.fromJSDate(stats.mtime);
  } catch (e) {
    return null;
  }
}

const parseDate = (value) => {
  if (!value) return null;
  if (DateTime.isDateTime(value)) return value;
  if (value instanceof Date) return DateTime.fromJSDate(value);
  const parsed = DateTime.fromISO(value);
  return parsed.isValid ? parsed : null;
}

const getPostCreatedAt = (data) => {
  const frontmatterDate = parseDate(data.createdAt);
  if (frontmatterDate) {
    return frontmatterDate;
  }
  const gitDate = getGitCreatedTime(data.page.inputPath);
  if (gitDate) {
    return gitDate;
  }
  const fileDate = getFileCreatedTime(data.page.inputPath);
  if (fileDate) {
    return fileDate;
  }

  return DateTime.fromJSDate(data.page.date);
}

module.exports = {
  layout: "post.njk",
  tags: ["posts"],
  eleventyComputed: {
    released: (data) => {
      if(data.page.inputPath.startsWith('./posts/drafts/')) {
        return false
      }
      
      return true
    },
    title: (data) => {
      if (data.title && data.title !== data.page.fileSlug) {
        return data.title;
      }
      return getTitleFromFilename(data.page.inputPath);
    },
    createdAt: getPostCreatedAt,
    updatedAt: (data) => {
      return parseDate(data.updatedAt) ?? 
        getGitModifiedTime(data.page.inputPath) ?? 
        getFileModifiedTime(data.page.inputPath);
    },
    permalink: (data) => {
      const title = data.title || getTitleFromFilename(data.page.inputPath);
      const slug = title.toLowerCase().replace(/\s+/g, '-').replace(/[^\w-]/g, '');

      const createdDate = getPostCreatedAt(data);
      
      const isoDate = createdDate.toISODate();
      return `/post/${slug}/${isoDate}/`;
    }
  }
};