import {Container} from '../../di'
import {Awaitable, Cache, ErrorWithContext, Maybe} from '../../util'
import {CacheModel} from './CacheModel'

/**
 * A cache driver whose records are stored in a database table using the CacheModel.
 */
export class ORMCache extends Cache {
    public async fetch(key: string): Promise<string | undefined> {
        return (await CacheModel.getCacheKey(key))?.cacheValue
    }

    public async put(key: string, value: string, expires?: Date): Promise<void> {
        let model = await CacheModel.findByKey<CacheModel>(key)
        if ( !model ) {
            model = <CacheModel> Container.getContainer().make(CacheModel)
        }

        model.cacheKey = key
        model.cacheValue = value
        model.cacheExpires = expires

        await model.save()
    }

    public async has(key: string): Promise<boolean> {
        return CacheModel.withCacheKey(key)
            .exists()
    }

    public async drop(key: string): Promise<void> {
        await CacheModel.query()
            .whereKey(key)
            .delete()
    }

    public async pop(key: string): Promise<string> {
        return CacheModel.getConnection()
            .asTransaction<string>(async () => {
                const model = await CacheModel.getCacheKey(key)
                if ( !model ) {
                    throw new ErrorWithContext('Cannot pop cache value: key does not exist.', {
                        key,
                    })
                }

                await model.delete()
                return model.cacheValue
            })
    }

    public increment(key: string, amount = 1): Awaitable<number> {
        return CacheModel.getConnection()
            .asTransaction<number>(async () => {
                const model = await CacheModel.getCacheKey(key)
                if ( !model ) {
                    await this.put(key, String(amount))
                    return amount
                }

                model.cacheValue = String(parseInt(model.cacheValue, 10) + amount)
                await model.save()
                return parseInt(model.cacheValue, 10)
            })
    }

    public decrement(key: string, amount = 1): Awaitable<number> {
        return CacheModel.getConnection()
            .asTransaction<number>(async () => {
                const model = await CacheModel.getCacheKey(key)
                if ( !model ) {
                    await this.put(key, String(-amount))
                    return amount
                }

                model.cacheValue = String(parseInt(model.cacheValue, 10) - amount)
                await model.save()
                return parseInt(model.cacheValue, 10)
            })
    }

    public async arrayPush(key: string, value: string): Promise<void> {
        await CacheModel.getConnection()
            .asTransaction<void>(async () => {
                const model = await CacheModel.getCacheKey(key)
                if ( !model ) {
                    await this.put(key, JSON.stringify([value]))
                    return
                }

                const cacheValue = JSON.parse(model.cacheValue)
                if ( !Array.isArray(cacheValue) ) {
                    throw new ErrorWithContext('Cannot push value to non-array.', {
                        key,
                    })
                }

                cacheValue.push(value)
                model.cacheValue = JSON.stringify(cacheValue)
            })

        throw new Error('Method not implemented.')
    }

    public async arrayPop(key: string): Promise<Maybe<string>> {
        return CacheModel.getConnection()
            .asTransaction<Maybe<string>>(async () => {
                const model = await CacheModel.getCacheKey(key)
                if ( !model ) {
                    return
                }

                const cacheValue = JSON.parse(model.cacheValue)
                if ( !Array.isArray(cacheValue) ) {
                    throw new ErrorWithContext('Cannot pop value from non-array.', {
                        key,
                    })
                }

                const value = cacheValue.pop()
                model.cacheValue = JSON.stringify(cacheValue)
                await model.save()
                return value
            })
    }
}