import { ActionConfig } from "../ActionConfig";
import { CommitInfo } from "./CommitInfo";
import { CommitInfoSet } from "./CommitInfoSet";
import { ReleaseInformation } from "./ReleaseInformation";
import { VersionClassification } from "./VersionClassification";
import { VersionClassifier } from "./VersionClassifier";
import { VersionType } from "./VersionType";

export class DefaultVersionClassifier implements VersionClassifier {

    protected majorPattern: (commit: CommitInfo) => boolean;
    protected minorPattern: (commit: CommitInfo) => boolean;
    protected enablePrereleaseMode: boolean;

    constructor(config: ActionConfig) {
        const searchBody = config.searchCommitBody;
        this.majorPattern = this.parsePattern(config.majorPattern, config.majorFlags, searchBody);
        this.minorPattern = this.parsePattern(config.minorPattern, config.minorFlags, searchBody);
        this.enablePrereleaseMode = config.enablePrereleaseMode;
    }

    protected parsePattern(pattern: string, flags: string, searchBody: boolean): (pattern: CommitInfo) => boolean {
        if (pattern.startsWith('/') && pattern.endsWith('/')) {
            var regex = new RegExp(pattern.slice(1, -1), flags);
            return searchBody ?
                (commit: CommitInfo) => regex.test(commit.subject) || regex.test(commit.body) :
                (commit: CommitInfo) => regex.test(commit.subject);
        } else {
            const matchString = pattern;
            return searchBody ?
                (commit: CommitInfo) => commit.subject.includes(matchString) || commit.body.includes(matchString) :
                (commit: CommitInfo) => commit.subject.includes(matchString);
        }
    }

    protected getNextVersion(current: ReleaseInformation, type: VersionType): ({ major: number, minor: number, patch: number }) {

        if (this.enablePrereleaseMode && current.major === 0) {
            switch (type) {
                case VersionType.Major:
                    return { major: current.major, minor: current.minor + 1, patch: 0 };
                case VersionType.Minor:
                case VersionType.Patch:
                    return { major: current.major, minor: current.minor, patch: current.patch + 1 };
                case VersionType.None:
                    return { major: current.major, minor: current.minor, patch: current.patch };
                default:
                    throw new Error(`Unknown change type: ${type}`);
            }
        }

        switch (type) {
            case VersionType.Major:
                return { major: current.major + 1, minor: 0, patch: 0 };
            case VersionType.Minor:
                return { major: current.major, minor: current.minor + 1, patch: 0 };
            case VersionType.Patch:
                return { major: current.major, minor: current.minor, patch: current.patch + 1 };
            case VersionType.None:
                return { major: current.major, minor: current.minor, patch: current.patch };
            default:
                throw new Error(`Unknown change type: ${type}`);
        }
    }

    private resolveCommitType(commitsSet: CommitInfoSet): ({ type: VersionType, increment: number, changed: boolean }) {
        if (commitsSet.commits.length === 0) {
            return { type: VersionType.None, increment: 0, changed: commitsSet.changed };
        }

        const commits = commitsSet.commits.reverse();
        let index = 1;
        for (let commit of commits) {
            if (this.majorPattern(commit)) {
                return { type: VersionType.Major, increment: commits.length - index, changed: commitsSet.changed };
            }
            index++;
        }

        index = 1;
        for (let commit of commits) {
            if (this.minorPattern(commit)) {
                return { type: VersionType.Minor, increment: commits.length - index, changed: commitsSet.changed };
            }
            index++;
        }

        return { type: VersionType.Patch, increment: commitsSet.commits.length - 1, changed: true };
    }

    public async ClassifyAsync(lastRelease: ReleaseInformation, commitSet: CommitInfoSet): Promise<VersionClassification> {

        const { type, increment, changed } = this.resolveCommitType(commitSet);

        const { major, minor, patch } = this.getNextVersion(lastRelease, type);

        if (lastRelease.currentPatch !== null) {
            // If the current commit is tagged, we must use that version. Here we check if the version we have resolved from the
            // previous commits is the same as the current version. If it is, we will use the increment value, otherwise we reset
            // to zero. For example:

            // - commit 1 - v1.0.0+0
            // - commit 2 - v1.0.0+1
            // - commit 3 was tagged v2.0.0 - v2.0.0+0
            // - commit 4 - v2.0.1+0

            const versionsMatch = lastRelease.currentMajor === major && lastRelease.currentMinor === minor && lastRelease.currentPatch === patch;
            const currentIncremement = versionsMatch ? increment : 0;
            return new VersionClassification(VersionType.None, currentIncremement, false, <number>lastRelease.currentMajor, <number>lastRelease.currentMinor, <number>lastRelease.currentPatch);
        }


        return new VersionClassification(type, increment, changed, major, minor, patch);
    }
}