import subprocess


class Commit:
    def __init__(self, commit_hash, author, vcc=None):
        self.commit_hash = commit_hash
        self.author = author
        self.is_vcc = vcc
        self.xp = None

    def get_experience(self, commits, exp_dir):
        if self.xp is None:
            with open(exp_dir + self.author.replace("/", "_")) as f:
                commit_history = f.readlines()
            for xp in range(len(commit_history)):
                commit_hash = commit_history[xp].split(',')[0]
                if commit_hash in commits.hash_to_commit:
                    commits.hash_to_commit[commit_hash].xp = xp
        assert self.xp is not None, "author: {}\ncommit: {}\nis vcc: {}"\
                   .format(self.author, self.commit_hash, self.is_vcc)
        return self.xp


class Commits:
    def __init__(self, git_dir, paths, vccs=None):
        """
        Returns a list of Commits at the given paths, ordered chronologically
        by authored time from old to new (NOT the order they were applied).
        paths is a single string appended raw to the git command,
        so any necessary escaping, quoting, etc. should be applied prior
        """
        command = "git -C " + git_dir + " log " \
            "--full-history --reverse --no-merges --use-mailmap " \
            "--since-as-filter=2012-04-09 " \
            "--format='format:%ct	%H	%aN <%aE>' -- " \
            + paths + " | sort -n | cut -f2,3"
        lines = subprocess.check_output(command, shell=True,
                                        universal_newlines=True).strip()
        assert lines, "git command failed to return any commits: {}"\
            .format(command)
        self.commits = []
        self.hash_to_commit = {}
        matched_vccs = set()
        for line in lines.splitlines():
            if '\\' in line:
                # dark incantation to unescape string
                line = line.encode('latin1').decode('unicode_escape').encode(
                    'latin1').decode('utf-8')
            line = line.strip().split('	')  # tab
            commit_hash = line[0]
            author = line[1]
            if vccs:
                vcc = commit_hash in vccs
                if vcc:
                    matched_vccs.add(commit_hash)
            else:
                vcc = None
            commit = Commit(line[0], author, vcc)
            self.commits.append(commit)
            self.hash_to_commit[commit_hash] = commit
        # unmatched_vccs = [vcc for vcc in vccs if vcc not in matched_vccs]
        # print("VCCs unmatched to any valid commit:", unmatched_vccs,
        #      file=sys.stderr, flush=True)


class GrowingList(list):
    def __init__(self, default):
        super().__init__()
        self.default = default

    def __setitem__(self, index, value):
        while index >= len(self):
            self.append(self.default())
        list.__setitem__(self, index, value)

    def __getitem__(self, index):
        while index >= len(self):
            self.append(self.default())
        return list.__getitem__(self, index)


class Counts:
    def __init__(self, total=0, vccs=0):
        self.total = total
        self.vccs = vccs


def count_commits(commits, vccs, exp_dir, counts=None):
    if not counts:
        counts = GrowingList(Counts)
    bugs = set()
    for commit in commits.commits:
        j = commit.get_experience(commits, exp_dir)
        if commit.is_vcc:
            for bug in vccs[commit.commit_hash]:
                if bug not in bugs:
                    counts[j].vccs += 1
                    bugs.add(bug)
        counts[j].total += 1
    return counts


def count_all_commits(git_dirs, project_paths, exp_dirs, vccs):
    assert len(git_dirs) == len(exp_dirs) and \
        len(git_dirs) == len(project_paths), \
        "each git dir needs one project path and one experience dir"

    counts = None
    for i in range(len(git_dirs)):
        commits = Commits(git_dirs[i], project_paths[i], vccs)
        counts = count_commits(commits, vccs, exp_dirs[i], counts)

    # convert to a normal list
    return [c for c in counts]


def get_vccs(vcc_file):
    vccs = {}
    with open(vcc_file) as f:
        for line in f.readlines():
            line = line.strip().split(',')
            issues = {issue for issue in line[1:]}
            if line[0] not in vccs:
                vccs[line[0]] = issues
            else:
                vccs[line[0]] |= issues
    return vccs


def expdirs(exp_dirs):
    for exp_dir in exp_dirs:
        if exp_dir[-1] != '/':
            exp_dir += '/'
    return exp_dirs


# takes an iterable of Decimal objects
def sigfigs(vals):
    msds = [v.adjusted() for v in vals]
    if not all(msd == msds[0] for msd in msds):
        msd = -max(msds)
        return [round(vals[i], msd) for i in range(len(vals))]

    for i in range(-msds[0], 20):  # arbitrarily high precision
        if any(round(v, i) != round(vals[0], i) for v in vals):
            return [round(v, i) for v in vals]
    return vals