import { Inject, Injectable } from '@nestjs/common';
import { MinioService } from 'src/minio/minio.service';
import Redis from 'ioredis'
import { InjectRedis } from '@liaoliaots/nestjs-redis';
import { CACHE_MANAGER } from '@nestjs/cache-manager';
import { Cache } from 'cache-manager';
import { aperture } from 'ramda';

export interface JobMetadata {
    name: string;
    description: string;
    tags: string[];
    createdBy: string;
    createdAt: string;
    claimSecret: string;
}

export const privateMetadataKeys = ['claimSecret'];

export type PublicJobMetadata = Omit<JobMetadata, typeof privateMetadataKeys[number]>;

type Leaderboard = { completeCounts: { [claimer: string]: number }, claimCounts: { [claimer: string]: number } }

@Injectable()
export class JobsService {
    constructor(
        private readonly minioService: MinioService,
        @InjectRedis() private readonly redis: Redis,
        @Inject(CACHE_MANAGER) private readonly cacheManager: Cache,
    ) { }

    public static cleanJobMetadata(metadata: JobMetadata): PublicJobMetadata {
        return Object.fromEntries(Object.entries(metadata).filter(([key]) => !privateMetadataKeys.includes(key))) as PublicJobMetadata;
    }

    private jobNameBuilder(jobName: string) {
        return `job:${jobName}`;
    }

    private todoListNameBuilder(jobName: string) {
        return `todo:${jobName}`;
    }

    private doneListNameBuilder(jobName: string) {
        return `done:${jobName}`;
    }

    private claimedListNameBuilder(jobName: string) {
        return `claimed:${jobName}`;
    }

    private completeCountNameBuilder(jobName: string, claimer: string) {
        return `complete:${jobName}:${claimer}`;
    }

    private claimerCountNameBuilder(jobName: string, claimer: string) {
        return `claim:${jobName}:${claimer}`;
    }

    private claimerCountWildcardBuilder(jobName: string) {
        return `claim:${jobName}:*`;
    }

    private async getCompleteCounts(jobName: string): Promise<{ [claimer: string]: number }> {
        const keys = await this.redis.keys(`complete:${jobName}:*`);
        const counts = await Promise.all(keys.map(async key => {
            const count = await this.redis.get(key);
            if (!count) {
                return null;
            }
            return { claimer: key.split(':')[2], count: parseInt(count) };
        }));
        return counts.reduce((acc: any, val: any) => {
            if (!val) {
                return acc;
            }
            acc[val.claimer] = val.count;
            return acc;
        }, {})
    }

    private async getClaimCounts(jobName: string): Promise<{ [claimer: string]: number }> {
        const keys = await this.redis.keys(`claim:${jobName}:*`);
        const counts = await Promise.all(keys.map(async key => {
            const count = await this.redis.get(key);
            if (!count) {
                return null;
            }
            return { claimer: key.split(':')[2], count: parseInt(count) };
        }));
        return counts.reduce((acc: any, val: any) => {
            if (!val) {
                return acc;
            }
            acc[val.claimer] = val.count;
            return acc;
        }, {});
    }

    async getLeaderboard(jobName: string): Promise<Leaderboard> {
        const cachedLeaderboard = await this.cacheManager.get<Leaderboard>(`leaderboard:${jobName}`);
        if (cachedLeaderboard) {
            return cachedLeaderboard;
        }
        const completeCounts = await this.getCompleteCounts(jobName);
        const claimCounts = await this.getClaimCounts(jobName);
        this.cacheManager.set(`leaderboard:${jobName}`, { completeCounts, claimCounts }, 200);
        return { completeCounts, claimCounts };
    }


    async addItemsToJob(jobName: string, items: string[]) {
        const apertureSize = 100
        for (const itemSubset of (items.length > apertureSize ? aperture(apertureSize, items) : [items])) {
            await this.redis.rpush(this.todoListNameBuilder(jobName), ...itemSubset);
        }
    }

    async claimJobItem(jobName: string, claimer: string): Promise<string | null> {
        const jobItem = await this.redis.brpoplpush(this.todoListNameBuilder(jobName), this.claimedListNameBuilder(jobName), 10);
        if (!jobItem) {
            return null;
        }
        await this.redis.incr(this.claimerCountNameBuilder(jobName, claimer));
        return jobItem;
    }

    async completeJobItem(jobName: string, jobItem: string, completer: string, data: any) {
        const claimRemoveResult = await this.redis.lrem(this.claimedListNameBuilder(jobName), 1, jobItem);
        if (claimRemoveResult === 0) {
            return false;
        }
        await this.redis.rpush(this.doneListNameBuilder(jobName), JSON.stringify({ item: jobItem, client: completer, data }));
        await this.redis.decr(this.claimerCountNameBuilder(jobName, completer));
        await this.redis.incr(this.completeCountNameBuilder(jobName, completer));
        return true
    }

    async getTodoItems(jobName: string) {
        return this.redis.lrange(this.todoListNameBuilder(jobName), 0, -1);
    }

    async getTodoItemCount(jobName: string) {
        return this.redis.llen(this.todoListNameBuilder(jobName));
    }

    async getClaimedItems(jobName: string) {
        return this.redis.lrange(this.claimedListNameBuilder(jobName), 0, -1);
    }

    async getClaimedItemCount(jobName: string) {
        return this.redis.llen(this.claimedListNameBuilder(jobName));
    }

    async getDoneItems(jobName: string) {
        return this.redis.lrange(this.doneListNameBuilder(jobName), 0, -1);
    }

    async getDoneItemCount(jobName: string) {
        return this.redis.llen(this.doneListNameBuilder(jobName));
    }

    async getJobs() {
        return this.redis.keys('job:*');
    }

    async isJobRegistered(jobName: string) {
        return this.redis.exists(this.jobNameBuilder(jobName));
    }

    async registerJob(jobName: string, metadata: JobMetadata) {
        if (await this.isJobRegistered(jobName)) {
            return false;
        }
        await this.redis.set(this.jobNameBuilder(jobName), JSON.stringify(metadata));
        return true
    }

    async getJobMetadata(jobName: string): Promise<JobMetadata | null> {
        const result = await this.redis.get(this.jobNameBuilder(jobName))
        if (!result) {
            return null;
        }
        return JSON.parse(result)
    }

    async getPublicJobMetadata(jobName: string): Promise<PublicJobMetadata | null> {
        const metadata = await this.getJobMetadata(jobName);
        if (!metadata) {
            return null;
        }
        return JobsService.cleanJobMetadata(metadata);
    }

    async clearClaimerCounts(jobName: string) {
        const keys = await this.redis.keys(this.claimerCountWildcardBuilder(jobName));
        await Promise.all(keys.map(key => this.redis.del(key)));
    }

    async resetClaimedItems(jobName: string) {
        const claimedItems = await this.getClaimedItems(jobName);
        for (const claimedItem of claimedItems) {
            await this.redis.rpoplpush(this.claimedListNameBuilder(jobName), this.todoListNameBuilder(jobName));
        }
        await this.clearClaimerCounts(jobName);
    }

    async clearTodoItems(jobName: string, claimKey: string) {
        const metadata = await this.getJobMetadata(jobName);
        if (metadata === null || metadata.claimSecret !== claimKey) {
            return false;
        }

        await this.redis.del(this.todoListNameBuilder(jobName));
    }

}