import { Job, Queue, Worker } from 'bullmq';
import { Redis } from 'ioredis';
import { createLogger } from "./logger.js";
import { Connection, PrismaClient, Repo, RepoToConnection, RepoIndexingStatus, StripeSubscriptionStatus } from "@sourcebot/db";
import { GithubConnectionConfig, GitlabConnectionConfig, GiteaConnectionConfig } from '@sourcebot/schemas/v3/connection.type';
import { AppContext, Settings, RepoMetadata } from "./types.js";
import { getRepoPath, getTokenFromConfig, measure, getShardPrefix } from "./utils.js";
import { cloneRepository, fetchRepository } from "./git.js";
import { existsSync, readdirSync, promises } from 'fs';
import { indexGitRepository } from "./zoekt.js";
import os from 'os';
import { PromClient } from './promClient.js';
import * as Sentry from "@sentry/node";
interface IRepoManager {
    blockingPollLoop: () => void;
    dispose: () => void;
}

const REPO_INDEXING_QUEUE = 'repoIndexingQueue';
const REPO_GC_QUEUE = 'repoGarbageCollectionQueue';

type RepoWithConnections = Repo & { connections: (RepoToConnection & { connection: Connection })[] };
type RepoIndexingPayload = {
    repo: RepoWithConnections,
}

type RepoGarbageCollectionPayload = {
    repo: Repo,
}

export class RepoManager implements IRepoManager {
    private indexWorker: Worker;
    private indexQueue: Queue<RepoIndexingPayload>;
    private gcWorker: Worker;
    private gcQueue: Queue<RepoGarbageCollectionPayload>;
    private logger = createLogger('RepoManager');

    constructor(
        private db: PrismaClient,
        private settings: Settings,
        redis: Redis,
        private promClient: PromClient,
        private ctx: AppContext,
    ) {
        const numCores = os.cpus().length;

        // Repo indexing
        this.indexQueue = new Queue<RepoIndexingPayload>(REPO_INDEXING_QUEUE, {
            connection: redis,
        });
        this.indexWorker = new Worker(REPO_INDEXING_QUEUE, this.runIndexJob.bind(this), {
            connection: redis,
            concurrency: numCores * this.settings.indexConcurrencyMultiple,
        });
        this.indexWorker.on('completed', this.onIndexJobCompleted.bind(this));
        this.indexWorker.on('failed', this.onIndexJobFailed.bind(this));

        // Garbage collection
        this.gcQueue = new Queue<RepoGarbageCollectionPayload>(REPO_GC_QUEUE, {
            connection: redis,
        });
        this.gcWorker = new Worker(REPO_GC_QUEUE, this.runGarbageCollectionJob.bind(this), {
            connection: redis,
            concurrency: numCores * this.settings.gcConcurrencyMultiple,
        });
        this.gcWorker.on('completed', this.onGarbageCollectionJobCompleted.bind(this));
        this.gcWorker.on('failed', this.onGarbageCollectionJobFailed.bind(this));
    }

    public async blockingPollLoop() {
        while (true) {
            await this.fetchAndScheduleRepoIndexing();
            await this.fetchAndScheduleRepoGarbageCollection();

            await new Promise(resolve => setTimeout(resolve, this.settings.reindexRepoPollingIntervalMs));
        }
    }

    ///////////////////////////
    // Repo indexing
    ///////////////////////////

    private async scheduleRepoIndexingBulk(repos: RepoWithConnections[]) {
        await this.db.$transaction(async (tx) => {
            await tx.repo.updateMany({
                where: { id: { in: repos.map(repo => repo.id) } },
                data: { repoIndexingStatus: RepoIndexingStatus.IN_INDEX_QUEUE }
            });

            const reposByOrg = repos.reduce<Record<number, RepoWithConnections[]>>((acc, repo) => {
                if (!acc[repo.orgId]) {
                    acc[repo.orgId] = [];
                }
                acc[repo.orgId].push(repo);
                return acc;
            }, {});

            for (const orgId in reposByOrg) {
                const orgRepos = reposByOrg[orgId];
                // Set priority based on number of repos (more repos = lower priority)
                // This helps prevent large orgs from overwhelming the indexQueue
                const priority = Math.min(Math.ceil(orgRepos.length / 10), 2097152);

                await this.indexQueue.addBulk(orgRepos.map(repo => ({
                    name: 'repoIndexJob',
                    data: { repo },
                    opts: {
                        priority: priority
                    }
                })));

                // Increment pending jobs counter for each repo added
                orgRepos.forEach(repo => {
                    this.promClient.pendingRepoIndexingJobs.inc({ repo: repo.id.toString() });
                });

                this.logger.info(`Added ${orgRepos.length} jobs to indexQueue for org ${orgId} with priority ${priority}`);
            }


        }).catch((err: unknown) => {
            this.logger.error(`Failed to add jobs to indexQueue for repos ${repos.map(repo => repo.id).join(', ')}: ${err}`);
        });
    }


    private async fetchAndScheduleRepoIndexing() {
        const thresholdDate = new Date(Date.now() - this.settings.reindexIntervalMs);
        const repos = await this.db.repo.findMany({
            where: {
                repoIndexingStatus: {
                    in: [
                        RepoIndexingStatus.NEW,
                        RepoIndexingStatus.INDEXED
                    ]
                },
                OR: [
                    { indexedAt: null },
                    { indexedAt: { lt: thresholdDate } },
                ]
            },
            include: {
                connections: {
                    include: {
                        connection: true
                    }
                }
            }
        });

        if (repos.length > 0) {
            await this.scheduleRepoIndexingBulk(repos);
        }
    }


    // TODO: do this better? ex: try using the tokens from all the connections 
    // We can no longer use repo.cloneUrl directly since it doesn't contain the token for security reasons. As a result, we need to
    // fetch the token here using the connections from the repo. Multiple connections could be referencing this repo, and each
    // may have their own token. This method will just pick the first connection that has a token (if one exists) and uses that. This
    // may technically cause syncing to fail if that connection's token just so happens to not have access to the repo it's referrencing.
    private async getTokenForRepo(repo: RepoWithConnections, db: PrismaClient) {
        const repoConnections = repo.connections;
        if (repoConnections.length === 0) {
            this.logger.error(`Repo ${repo.id} has no connections`);
            return;
        }


        let token: string | undefined;
        for (const repoConnection of repoConnections) {
            const connection = repoConnection.connection;
            if (connection.connectionType !== 'github' && connection.connectionType !== 'gitlab' && connection.connectionType !== 'gitea') {
                continue;
            }

            const config = connection.config as unknown as GithubConnectionConfig | GitlabConnectionConfig | GiteaConnectionConfig;
            if (config.token) {
                const tokenResult = await getTokenFromConfig(config.token, connection.orgId, db);
                token = tokenResult?.token;
                if (token) {
                    break;
                }
            }
        }

        return token;
    }

    private async syncGitRepository(repo: RepoWithConnections, repoAlreadyInIndexingState: boolean) {
        let fetchDuration_s: number | undefined = undefined;
        let cloneDuration_s: number | undefined = undefined;

        const repoPath = getRepoPath(repo, this.ctx);
        const metadata = repo.metadata as RepoMetadata;

        
        // If the repo was already in the indexing state, this job was likely killed and picked up again. As a result,
        // to ensure the repo state is valid, we delete the repo if it exists so we get a fresh clone 
        if (repoAlreadyInIndexingState && existsSync(repoPath)) {
            this.logger.info(`Deleting repo directory ${repoPath} during sync because it was already in the indexing state`);
            await promises.rm(repoPath, { recursive: true, force: true });      
        }

        if (existsSync(repoPath)) {
            this.logger.info(`Fetching ${repo.id}...`);

            const { durationMs } = await measure(() => fetchRepository(repoPath, ({ method, stage, progress }) => {
                //this.logger.info(`git.${method} ${stage} stage ${progress}% complete for ${repo.id}`)
            }));
            fetchDuration_s = durationMs / 1000;

            process.stdout.write('\n');
            this.logger.info(`Fetched ${repo.name} in ${fetchDuration_s}s`);

        } else {
            this.logger.info(`Cloning ${repo.id}...`);

            const token = await this.getTokenForRepo(repo, this.db);
            let cloneUrl = repo.cloneUrl;
            if (token) {
                const url = new URL(cloneUrl);
                url.username = token;
                cloneUrl = url.toString();
            }

            const { durationMs } = await measure(() => cloneRepository(cloneUrl, repoPath, metadata.gitConfig, ({ method, stage, progress }) => {
                //this.logger.info(`git.${method} ${stage} stage ${progress}% complete for ${repo.id}`)
            }));
            cloneDuration_s = durationMs / 1000;

            process.stdout.write('\n');
            this.logger.info(`Cloned ${repo.id} in ${cloneDuration_s}s`);
        }

        this.logger.info(`Indexing ${repo.id}...`);
        const { durationMs } = await measure(() => indexGitRepository(repo, this.ctx));
        const indexDuration_s = durationMs / 1000;
        this.logger.info(`Indexed ${repo.id} in ${indexDuration_s}s`);

        return {
            fetchDuration_s,
            cloneDuration_s,
            indexDuration_s,
        }
    }

    private async runIndexJob(job: Job<RepoIndexingPayload>) {
        this.logger.info(`Running index job (id: ${job.id}) for repo ${job.data.repo.id}`);
        const repo = job.data.repo as RepoWithConnections;

        // We have to use the existing repo object to get the repoIndexingStatus because the repo object
        // inside the job is unchanged from when it was added to the queue.
        const existingRepo = await this.db.repo.findUnique({
            where: {
                id: repo.id,
            },
        });
        if (!existingRepo) {
            this.logger.error(`Repo ${repo.id} not found`);
            const e = new Error(`Repo ${repo.id} not found`);
            Sentry.captureException(e);
            throw e;
        }
        const repoAlreadyInIndexingState = existingRepo.repoIndexingStatus === RepoIndexingStatus.INDEXING;


        await this.db.repo.update({
            where: {
                id: repo.id,
            },
            data: {
                repoIndexingStatus: RepoIndexingStatus.INDEXING,
            }
        });
        this.promClient.activeRepoIndexingJobs.inc();
        this.promClient.pendingRepoIndexingJobs.dec({ repo: repo.id.toString() });

        let indexDuration_s: number | undefined;
        let fetchDuration_s: number | undefined;
        let cloneDuration_s: number | undefined;

        let stats;
        let attempts = 0;
        const maxAttempts = 3;

        while (attempts < maxAttempts) {
            try {
                stats = await this.syncGitRepository(repo, repoAlreadyInIndexingState);
                break;
            } catch (error) {
                Sentry.captureException(error);

                attempts++;
                this.promClient.repoIndexingReattemptsTotal.inc();
                if (attempts === maxAttempts) {
                    this.logger.error(`Failed to sync repository ${repo.id} after ${maxAttempts} attempts. Error: ${error}`);
                    throw error;
                }

                const sleepDuration = 5000 * Math.pow(2, attempts - 1);
                this.logger.error(`Failed to sync repository ${repo.id}, attempt ${attempts}/${maxAttempts}. Sleeping for ${sleepDuration / 1000}s... Error: ${error}`);
                await new Promise(resolve => setTimeout(resolve, sleepDuration));
            }
        }

        indexDuration_s = stats!.indexDuration_s;
        fetchDuration_s = stats!.fetchDuration_s;
        cloneDuration_s = stats!.cloneDuration_s;
    }

    private async onIndexJobCompleted(job: Job<RepoIndexingPayload>) {
        this.logger.info(`Repo index job ${job.id} completed`);
        this.promClient.activeRepoIndexingJobs.dec();
        this.promClient.repoIndexingSuccessTotal.inc();

        await this.db.repo.update({
            where: {
                id: job.data.repo.id,
            },
            data: {
                indexedAt: new Date(),
                repoIndexingStatus: RepoIndexingStatus.INDEXED,
            }
        });
    }

    private async onIndexJobFailed(job: Job<RepoIndexingPayload> | undefined, err: unknown) {
        this.logger.info(`Repo index job failed (id: ${job?.id ?? 'unknown'})`);
        if (job) {
            this.promClient.activeRepoIndexingJobs.dec();
            this.promClient.repoIndexingFailTotal.inc();

            await this.db.repo.update({
                where: {
                    id: job.data.repo.id,
                },
                data: {
                    repoIndexingStatus: RepoIndexingStatus.FAILED,
                    indexedAt: new Date(),
                }
            })
        }
    }

    ///////////////////////////
    // Repo garbage collection
    ///////////////////////////

    private async scheduleRepoGarbageCollectionBulk(repos: Repo[]) {
        await this.db.$transaction(async (tx) => {
            await tx.repo.updateMany({
                where: { id: { in: repos.map(repo => repo.id) } },
                data: { repoIndexingStatus: RepoIndexingStatus.IN_GC_QUEUE }
            });

            await this.gcQueue.addBulk(repos.map(repo => ({
                name: 'repoGarbageCollectionJob',
                data: { repo },
            })));

            this.logger.info(`Added ${repos.length} jobs to gcQueue`);
        });
    }

    private async fetchAndScheduleRepoGarbageCollection() {
        ////////////////////////////////////
        // Get repos with no connections
        ////////////////////////////////////


        const thresholdDate = new Date(Date.now() - this.settings.gcGracePeriodMs);
        const reposWithNoConnections = await this.db.repo.findMany({
            where: {
                repoIndexingStatus: {
                    in: [
                        RepoIndexingStatus.INDEXED, // we don't include NEW repos here because they'll be picked up by the index queue (potential race condition)
                        RepoIndexingStatus.FAILED,
                    ]
                },
                connections: {
                    none: {}
                },
                OR: [
                    { indexedAt: null },
                    { indexedAt: { lt: thresholdDate } }
                ]
            },
        });
        if (reposWithNoConnections.length > 0) {
            this.logger.info(`Garbage collecting ${reposWithNoConnections.length} repos with no connections: ${reposWithNoConnections.map(repo => repo.id).join(', ')}`);
        }

        ////////////////////////////////////
        // Get inactive org repos
        ////////////////////////////////////
        const sevenDaysAgo = new Date(Date.now() - 7 * 24 * 60 * 60 * 1000);
        const inactiveOrgRepos = await this.db.repo.findMany({
            where: {
                org: {
                    stripeSubscriptionStatus: StripeSubscriptionStatus.INACTIVE,
                    stripeLastUpdatedAt: {
                        lt: sevenDaysAgo
                    }
                },
                OR: [
                    { indexedAt: null },
                    { indexedAt: { lt: thresholdDate } }
                ]
            }
        });

        if (inactiveOrgRepos.length > 0) {
            this.logger.info(`Garbage collecting ${inactiveOrgRepos.length} inactive org repos: ${inactiveOrgRepos.map(repo => repo.id).join(', ')}`);
        }

        const reposToDelete = [...reposWithNoConnections, ...inactiveOrgRepos];
        if (reposToDelete.length > 0) {
            await this.scheduleRepoGarbageCollectionBulk(reposToDelete);
        }
    }

    private async runGarbageCollectionJob(job: Job<RepoGarbageCollectionPayload>) {
        this.logger.info(`Running garbage collection job (id: ${job.id}) for repo ${job.data.repo.id}`);
        this.promClient.activeRepoGarbageCollectionJobs.inc();

        const repo = job.data.repo as Repo;
        await this.db.repo.update({
            where: {
                id: repo.id
            },
            data: {
                repoIndexingStatus: RepoIndexingStatus.GARBAGE_COLLECTING
            }
        });

        // delete cloned repo
        const repoPath = getRepoPath(repo, this.ctx);
        if (existsSync(repoPath)) {
            this.logger.info(`Deleting repo directory ${repoPath}`);
            await promises.rm(repoPath, { recursive: true, force: true });      
        }

        // delete shards
        const shardPrefix = getShardPrefix(repo.orgId, repo.id);
        const files = readdirSync(this.ctx.indexPath).filter(file => file.startsWith(shardPrefix));
        for (const file of files) {
            const filePath = `${this.ctx.indexPath}/${file}`;
            this.logger.info(`Deleting shard file ${filePath}`);
            await promises.rm(filePath, { force: true });
        }
    }

    private async onGarbageCollectionJobCompleted(job: Job<RepoGarbageCollectionPayload>) {
        this.logger.info(`Garbage collection job ${job.id} completed`);
        this.promClient.activeRepoGarbageCollectionJobs.dec();
        this.promClient.repoGarbageCollectionSuccessTotal.inc();

        await this.db.repo.delete({
            where: {
                id: job.data.repo.id
            }
        });
    }

    private async onGarbageCollectionJobFailed(job: Job<RepoGarbageCollectionPayload> | undefined, err: unknown) {
        this.logger.info(`Garbage collection job failed (id: ${job?.id ?? 'unknown'}) with error: ${err}`);

        if (job) {
            this.promClient.activeRepoGarbageCollectionJobs.dec();
            this.promClient.repoGarbageCollectionFailTotal.inc();

            await this.db.repo.update({
                where: {
                    id: job.data.repo.id
                },
                data: {
                    repoIndexingStatus: RepoIndexingStatus.GARBAGE_COLLECTION_FAILED
                }
            });
        }
    }

    public async dispose() {
        this.indexWorker.close();
        this.indexQueue.close();
        this.gcQueue.close();
        this.gcWorker.close();
    }
}