"use strict";

var events = require("events");
var fp = require("lodash/fp");
var NodeGit = require("../");
var Commit = NodeGit.Commit;
var LookupWrapper = NodeGit.Utils.lookupWrapper;

var _amend = Commit.prototype.amend;

/**
 * Retrieves the commit pointed to by the oid
 * @async
 * @param {Repository} repo The repo that the commit lives in
 * @param {String|Oid|Commit} id The commit to lookup
 * @return {Commit}
 */
Commit.lookup = LookupWrapper(Commit);

/**
 * Amend a commit
 * @async
 * @param {String} update_ref
 * @param {Signature} author
 * @param {Signature} committer
 * @param {String} message_encoding
 * @param {String} message
 * @param {Tree|Oid} tree
 * @param {Oid} callback
 */
Commit.prototype.amend = function (updateRef, author, committer, message_encoding, message, tree, callback) {
  var repo = this.repo;
  var _this = this;
  var treePromise;

  if (tree instanceof NodeGit.Oid) {
    treePromise = repo.getTree(tree);
  } else {
    treePromise = Promise.resolve(tree);
  }

  return treePromise.then(function (treeObject) {
    return _amend.call(_this, updateRef, author, committer, message_encoding, message, treeObject);
  });
};

/**
 * Amend a commit with the given signature
 * @async
 * @param {String} updateRef
 * @param {Signature} author
 * @param {Signature} committer
 * @param {String} messageEncoding
 * @param {String} message
 * @param {Tree|Oid} tree
 * @param {String} signatureField
 * @param {Function} onSignature
 * @return {Oid}
*/
Commit.prototype.amendWithSignature = function (updateRef, author, committer, messageEncoding, message, tree, signatureField, onSignature) {
  var repo = this.repo;
  var parentOids = this.parents();
  var _this = this;
  var promises = [];

  if (tree instanceof NodeGit.Oid) {
    promises.push(repo.getTree(tree));
  } else {
    promises.push(Promise.resolve(tree));
  }

  parentOids.forEach(function (parentOid) {
    promises.push(repo.getCommit(parentOid));
  });

  var treeObject;
  var parents;
  var commitContent;
  var commitOid;
  var commit;

  var createCommitPromise = Promise.all(promises).then(function (results) {
    treeObject = fp.head(results);
    parents = fp.tail(results);
    return _this.getTree();
  }).then(function (commitTreeResult) {
    var commitTree = commitTreeResult;

    var truthyArgs = fp.omitBy(fp.isNil, {
      author: author,
      committer: committer,
      messageEncoding: messageEncoding,
      message: message,
      tree: treeObject
    });

    var commitFields = {
      author: _this.author(),
      committer: _this.committer(),
      messageEncoding: _this.messageEncoding(),
      message: _this.message(),
      tree: commitTree
    };

    var _fp$assign = fp.assign(commitFields, truthyArgs),
        resolvedAuthor = _fp$assign.author,
        resolvedCommitter = _fp$assign.committer,
        resolvedMessageEncoding = _fp$assign.messageEncoding,
        resolvedMessage = _fp$assign.message,
        resolvedTree = _fp$assign.tree;

    return Commit.createBuffer(repo, resolvedAuthor, resolvedCommitter, resolvedMessageEncoding, resolvedMessage, resolvedTree, parents.length, parents);
  }).then(function (commitContentResult) {
    commitContent = commitContentResult;
    if (!commitContent.endsWith("\n")) {
      commitContent += "\n";
    }
    return onSignature(commitContent);
  }).then(function (signature) {
    return Commit.createWithSignature(repo, commitContent, signature, signatureField);
  });

  if (!updateRef) {
    return createCommitPromise;
  }

  return createCommitPromise.then(function (commitOidResult) {
    commitOid = commitOidResult;
    return repo.getCommit(commitOid);
  }).then(function (commitResult) {
    commit = commitResult;
    return repo.getReference(updateRef);
  }).then(function (ref) {
    return ref.setTarget(commitOid, "commit (amend): " + commit.summary());
  }).then(function () {
    return commitOid;
  });
};

/**
 * Retrieve the commit time as a Date object.
 * @return {Date}
 */
Commit.prototype.date = function () {
  return new Date(this.timeMs());
};

/**
 * Generate an array of diff trees showing changes between this commit
 * and its parent(s).
 *
 * @async
 * @param {Function} callback
 * @return {Array<Diff>} an array of diffs
 */
Commit.prototype.getDiff = function (callback) {
  return this.getDiffWithOptions(null, callback);
};

/**
 * Generate an array of diff trees showing changes between this commit
 * and its parent(s).
 *
 * @async
 * @param {Object} options
 * @param {Function} callback
 * @return {Array<Diff>} an array of diffs
 */
Commit.prototype.getDiffWithOptions = function (options, callback) {
  var commit = this;

  return commit.getTree().then(function (thisTree) {
    return commit.getParents().then(function (parents) {
      var diffs;
      if (parents.length) {
        diffs = parents.map(function (parent) {
          return parent.getTree().then(function (parentTree) {
            return thisTree.diffWithOptions(parentTree, options);
          });
        });
      } else {
        diffs = [thisTree.diffWithOptions(null, options)];
      }

      return Promise.all(diffs);
    });
  }).then(function (diffs) {
    if (typeof callback === "function") {
      callback(null, diffs);
    }

    return diffs;
  }, callback);
};

/**
 * Retrieve the entry represented by path for this commit.
 * Path must be relative to repository root.
 *
 * @async
 * @param {String} path
 * @return {TreeEntry}
 */
Commit.prototype.getEntry = function (path, callback) {
  return this.getTree().then(function (tree) {
    return tree.getEntry(path).then(function (entry) {
      if (typeof callback === "function") {
        callback(null, entry);
      }

      return entry;
    });
  }, callback);
};

/**
 * Retrieve the commit's parents as commit objects.
 *
 * @async
 * @param {number} limit Optional amount of parents to return.
 * @param {Function} callback
 * @return {Array<Commit>} array of commits
 */
Commit.prototype.getParents = function (limit, callback) {
  var parents = [];

  // Shift arguments.
  if (typeof limit === "function") {
    callback = limit;
  }

  // If no limit was set, default to the maximum parents.
  limit = typeof limit === "number" ? limit : this.parentcount();
  limit = Math.min(limit, this.parentcount());

  for (var i = 0; i < limit; i++) {
    var oid = this.parentId(i);
    var parent = this.repo.getCommit(oid);

    parents.push(parent);
  }

  // Wait for all parents to complete, before returning.
  return Promise.all(parents).then(function (parents) {
    if (typeof callback === "function") {
      callback(null, parents);
    }

    return parents;
  }, callback);
};

/**
 * @typedef extractedSignature
 * @type {Object}
 * @property {String} signature the signature of the commit
 * @property {String} signedData the extracted signed data
 */

/**
 * Retrieve the signature and signed data for a commit.
 * @param  {String} field Optional field to get from the signature,
 *                        defaults to gpgsig
 * @return {extractedSignature}
 */
Commit.prototype.getSignature = function (field) {
  return Commit.extractSignature(this.repo, this.id(), field);
};

/**
 * Get the tree associated with this commit.
 *
 * @async
 * @return {Tree}
 */
Commit.prototype.getTree = function (callback) {
  return this.repo.getTree(this.treeId(), callback);
};

/**
 * Walk the history from this commit backwards.
 *
 * An EventEmitter is returned that will emit a "commit" event for each
 * commit in the history, and one "end" event when the walk is completed.
 * Don't forget to call `start()` on the returned event.
 *
 * @fires EventEmitter#commit Commit
 * @fires EventEmitter#end Array<Commit>
 * @fires EventEmitter#error Error
 *
 * @return {EventEmitter}
 * @start start()
 */
Commit.prototype.history = function () {
  var event = new events.EventEmitter();
  var oid = this.id();
  var revwalk = this.repo.createRevWalk();

  revwalk.sorting.apply(revwalk, arguments);

  var commits = [];

  event.start = function () {
    revwalk.walk(oid, function commitRevWalk(error, commit) {
      if (error) {
        if (error.errno === NodeGit.Error.CODE.ITEROVER) {
          event.emit("end", commits);
          return;
        } else {
          return event.emit("error", error);
        }
      }

      event.emit("commit", commit);
      commits.push(commit);
    });
  };

  return event;
};

/**
 * Retrieve the commit's parent shas.
 *
 * @return {Array<Oid>} array of oids
 */
Commit.prototype.parents = function () {
  var result = [];

  for (var i = 0; i < this.parentcount(); i++) {
    result.push(this.parentId(i));
  }

  return result;
};

/**
 * Retrieve the SHA.
 * @return {String}
 */
Commit.prototype.sha = function () {
  return this.id().toString();
};

/**
 * Retrieve the commit time as a unix timestamp.
 * @return {Number}
 */
Commit.prototype.timeMs = function () {
  return this.time() * 1000;
};

/**
 * The sha of this commit
 * @return {String}
 */
Commit.prototype.toString = function () {
  return this.sha();
};