/*
 * Copyright © 2019 Atomist, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import {
    LocalProject,
} from "@atomist/automation-client";
import {
    Aspect,
    ExtractFingerprint,
    fingerprintOf,
} from "@atomist/sdm-pack-fingerprint";
import * as child_process from "child_process";
import * as util from "util";
import {
    bandFor,
    Default,
} from "../../util/bands";
import {
    AgeBands,
    SizeBands,
} from "../../util/commonBands";
import { showTiming } from "../../util/showTiming";
import {
    CountAspect,
    CountData,
} from "../compose/commonTypes";
import { daysSince } from "./dateUtils";

const exec = util.promisify(child_process.exec);

const gitLastCommitCommand = "git log -1 --format=%cd --date=short";

export const GitRecencyType = "git-recency";

export interface GitRecencyData {
    lastCommitTime: number;
}

const gitRecencyExtractor: ExtractFingerprint<GitRecencyData> =
    async p => {
        const r = await exec(gitLastCommitCommand, { cwd: (p as LocalProject).baseDir });
        if (!r.stdout) {
            return undefined;
        }
        const data = { lastCommitTime: new Date(r.stdout.trim()).getTime() };

        return fingerprintOf({
            type: GitRecencyType,
            data,
        });
    };

/**
 * Classify since last commit
 */
export const GitRecency: Aspect<GitRecencyData> = {
    name: GitRecencyType,
    displayName: "Recency of git activity",
    baseOnly: true,
    extract: gitRecencyExtractor,
    toDisplayableFingerprintName: () => "Recency of git activity",
    toDisplayableFingerprint: fp => {
        const date = new Date(fp.data.lastCommitTime);
        return lastDateToActivityBand(date);
    },
    stats: {
        defaultStatStatus: {
            entropy: false,
        },
    },
};

function committersCommands(commitDepth: number): string[] {
    return [
        `git fetch --depth=${commitDepth}`,
        `git shortlog -s -n --all --max-count ${commitDepth}`,
    ];
}

export const GitActivesType = "git-actives";

function activeCommittersExtractor(commitDepth: number): ExtractFingerprint<CountData> {
    return async p => {
        const cwd = (p as LocalProject).baseDir;
        const cmds = committersCommands(commitDepth);
        const r = await showTiming(`commands ${cmds} in ${cwd}`, async () => {
            exec(cmds[0], { cwd });
            return exec(cmds[1], { cwd });
        });
        if (!r.stdout) {
            return undefined;
        }
        const count = r.stdout.trim().split("\n").length;
        const data = { count };

        return fingerprintOf({
            type: GitActivesType,
            data,
        });
    };
}

/**
 * Active committers. This is expensive as it requires cloning the
 * last commitDepth commits
 */
export function gitActiveCommitters(opts: { commitDepth: number}): CountAspect {
    return {
        name: GitActivesType,
        displayName: "Active git committers",
        baseOnly: true,
        extract: activeCommittersExtractor(opts.commitDepth),
        toDisplayableFingerprintName: () => `Active git committers to ${opts.commitDepth} commits`,
        toDisplayableFingerprint: fp => {
            return bandFor<SizeBands>({
                low: { upTo: 4 },
                medium: { upTo: 12 },
                high: Default,
            }, fp.data.count, { includeNumber: true });
        },
        stats: {
            defaultStatStatus: {
                entropy: false,
            },
            basicStatsPath: "count",
        },
    };
}

function lastDateToActivityBand(date: Date): string {
    const days = daysSince(date);
    return bandFor<AgeBands>({
        current: { upTo: 30 },
        recent: { upTo: 200 },
        ancient: { upTo: 500 },
        prehistoric: Default,
    }, days, { includeNumber: true });
}