var _ = require('lodash');
var GitHub = require('github');
var github = new GitHub({ version: '3.0.0', 'User-Agent': 'hadron-build' });

github.authenticate({
  token: process.env.GITHUB_TOKEN,
  type: 'oauth'
});

var owner = '10gen';
var repo = 'compass';
var base = '1.6-releases';
var head = '1.7-releases';

var changelog = {
  compare_url: `https://github.com/${owner}/${repo}/compare/${base}...${head}`,
  stats: {
    total_commits: 0,
    ignored_commits: 0,
    include_jira: 0,
    include_jira_unique: 0,
    include_pr: 0,
    include_pr_unique: 0
  },
  ignored: [],
  jira: [],
  pr: [],
  featured: [],
  messages: [],
  other: []
};

function extractLinksFromCommit(commit) {
  // console.log('parse', commit);
  var message = _.trimStart(_.first(commit.commit.message.split('\n')));
  var res = {
    sha: commit.sha,
    original: message,
    message: message,
    jira: undefined,
    pr: undefined,
    author: commit.author.name
  };

  var m = /compass[-\s]?(\d+)/gi.exec(res.message);
  if (m) {
    res.jira = `COMPASS-${m[1]}`.toUpperCase();
    res.message = res.message.replace(m[0], `[${res.jira}][${res.jira}]`);
  }

  var pr = /\(#(\d+)\)/.exec(res.message);
  if (pr) {
    res.pr = pr[1];
    res.message = res.message.replace(
      `#${pr[1]}`,
      `[#${res.pr}][pr-${res.pr}]`
    );
  }

  return res;
}

var async = require('async');
var fs = require('fs');
var path = require('path');

function getPullRequestDetail(pr, cb) {
  var dest = path.join(__dirname, '..', 'pr-cache', `${pr}.json`);

  fs.readFile(dest, function(err, d) {
    if (!err) {
      return cb(null, JSON.parse(d));
    }

    github.pullRequests.get(
      { owner: owner, repo: repo, number: Number(pr) },
      function(err, res) {
        if (err) return cb(err);

        fs.writeFile(dest, JSON.stringify(res, null, 2), function(err) {
          if (err) return cb(err);
          cb(null, res);
        });
      }
    );
  });
}

function getAllPullRequests(done) {
  var tasks = changelog.pr.map(function(pr) {
    return function(cb) {
      getPullRequestDetail(pr, cb);
    };
  });
  return async.series(tasks, done);
}

function parseCommits(commits, done) {
  changelog.stats.total_commits = commits.length;

  var tasks = commits.map(function(commit) {
    return function(cb) {
      var res = extractLinksFromCommit(commit);
      if (!res.jira && !res.pr) {
        changelog.ignored.push(res);
        changelog.stats.ignored_commits += 1;
        return cb();
      }

      if (_.startsWith(res.message, 'Revert')) {
        changelog.ignored.push(res);
        changelog.stats.ignored_commits += 1;
        return cb();
      }

      if (res.jira) {
        if (changelog.jira.indexOf(res.jira) === -1) {
          changelog.stats.include_jira_unique += 1;
        }
        changelog.stats.include_jira += 1;
        changelog.jira.push(res.jira);
      }

      if (res.pr) {
        if (changelog.pr.indexOf(res.pr) === -1) {
          changelog.stats.include_pr_unique += 1;
        }
        changelog.stats.include_pr += 1;
        changelog.pr.push(res.pr);
      }
      if (
        res.pr &&
        res.jira &&
        changelog.messages.indexOf(res.message) === -1
      ) {
        changelog.messages.push(res.message);
        getPullRequestDetail(res.pr, function(_err, detail) {
          if (detail.body.indexOf('![') > -1) {
            changelog.featured.push({ title: res.message, body: detail.body });
          }
          cb();
        });
      } else {
        if (changelog.other.indexOf(res.message) === -1) {
          changelog.other.push(res.message);
        }
        return cb();
      }
    };
  });

  async.series(tasks, done);
}

github.repos.compareCommits(
  {
    owner: owner,
    repo: repo,
    base: base,
    head: head
  },
  function(err, res) {
    if (err) return console.log('err', err);
    changelog.messages = changelog.messages.sort();
    changelog.pr = changelog.pr.sort();
    changelog.jira = changelog.jira.sort();

    parseCommits(res.commits, function(_err) {
      if (_err) return console.log('err', _err);

      var contents = '';
      contents += '\n\n### Featured\n\n';
      changelog.featured.forEach(function(f) {
        contents += `#### ${f.title}\n\n${f.body}\n\n`;
      });

      contents += `\n\n### Whats New ${changelog.messages.length}\n\n`;
      changelog.messages.forEach(function(message) {
        contents += `- ${message}\n`;
      });

      contents += `\n\n### Other Changes ${changelog.other.length}\n\n`;

      changelog.other.forEach(function(message) {
        contents += `- ${message}\n`;
      });

      contents += `\n\n
    <!--
    Pull Requests:
      Total: ${changelog.stats.include_pr}
      Unique: ${changelog.stats.include_pr_unique}
    -->
  `;

      changelog.pr.forEach(function(pr) {
        contents += `[pr-${pr}]: https://github.com/10gen/compass/pull/${pr}\n`;
      });

      contents += `\n\n
    <!--
    JIRA Tickets:
      Total: ${changelog.stats.include_jira}
      Unique: ${changelog.stats.include_jira_unique}
    -->
  `;
      changelog.jira.forEach(function(jiraId) {
        contents += `[${jiraId}]: https://jira.mongodb.org/browse/${jiraId}\n`;
      });

      console.log(contents);
    });
  }
);