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

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 new Date(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 new Date(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);
    return stats.birthtime || stats.mtime;
  } catch (e) {
    return null;
  }
}

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

const parseDate = (value) => {
  if (!value) return null;
  if (value instanceof Date) return value;
  const parsed = new Date(value);
  return isNaN(parsed.getTime()) ? null : parsed;
}

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 data.page.date;
}

module.exports = {
  layout: "post.njk",
  tags: ["posts"],
  unreleased: false,
  eleventyComputed: {
    title: (data) => {
      if (data.title && data.title !== data.page.fileSlug) {
        return data.title;
      }
      return getTitleFromFilename(data.page.inputPath);
    },
    createdAt: getPostCreatedAt,
    updatedAt: (data) => {
      const modifiedDate = parseDate(data.updatedAt) ?? 
        getGitModifiedTime(data.page.inputPath) ?? 
        getFileModifiedTime(data.page.inputPath);
      const createdDate = getPostCreatedAt(data);

      if (modifiedDate) {
        // Only return updatedAt if it's AFTER created date (by more than a day)
        const dayInMs = 24 * 60 * 60 * 1000;
        if (modifiedDate > createdDate && (modifiedDate - createdDate) > dayInMs) {
          return modifiedDate;
        }
      }
      return createdDate;
    },
    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.toISOString().split('T')[0];
      return `/post/${slug}/${isoDate}/`;
    }
  }
};