import { Types, Model, FilterQuery } from 'mongoose';
import { ShrimpCrud } from './Shrimp';
import { IShrimpQuery, IShrimpCondition, IShrimpPopulate, IPageResult, ShrimpConfig, isShrimpCondition } from './IShrimpType';

export class MongoShrimpCrud<T> implements ShrimpCrud<T> {
    constructor(private model: Model<any>) { }

    /** 获取关联模块的 Mongoose Model（用于 populate / $lookup） */
    getRelatedModel?: (moduleKey: string) => Model<any> | undefined

    /** 判断值是否为 IShrimpCondition 对象 */
    private isCondition = isShrimpCondition

    /** 将 IShrimpCondition 翻译为 MongoDB 查询片段 */
    private translateCondition(cond: IShrimpCondition | any): any {
        if (!this.isCondition(cond)) return cond  // 简写: 原始值 = eq
        const q: any = {}
        if (cond.eq !== undefined) q.$eq = cond.eq
        if (cond.in !== undefined) q.$in = cond.in
        if (cond.like !== undefined) q.$regex = cond.like, q.$options = 'i'
        if (cond.gte !== undefined) q.$gte = cond.gte
        if (cond.lte !== undefined) q.$lte = cond.lte
        return q
    }

    /** 将 IShrimpQuery 翻译为 Mongoose 查询 */
    private buildMongooseQuery(query?: IShrimpQuery): { filter: FilterQuery<T>, sort: any, skip: number, limit: number } {
        const filter: FilterQuery<T> = {}

        // where → AND 条件
        if (query?.where) {
            for (const [key, cond] of Object.entries(query.where)) {
                (filter as any)[key] = this.translateCondition(cond)
            }
        }

        // orWhere → $or
        if (query?.orWhere && query.orWhere.length > 0) {
            filter.$or = query.orWhere.map(group => {
                const obj: any = {}
                for (const [key, cond] of Object.entries(group)) {
                    obj[key] = this.translateCondition(cond)
                }
                return obj
            })
        }

        // 排序
        const sort: any = {}
        if (query?.order) {
            for (const [key, dir] of query.order) {
                sort[key] = dir === 'desc' ? -1 : 1
            }
        }

        return {
            filter,
            sort,
            skip: query?.offset || 0,
            limit: query?.limit ?? ShrimpConfig.defaultPageSize,
        }
    }

    async list(query?: IShrimpQuery): Promise<IPageResult<T>> {
        const { filter, sort, skip, limit } = this.buildMongooseQuery(query)

        const [docs, total] = await Promise.all([
            this.model.find(filter).sort(sort).skip(skip).limit(limit).lean(),
            this.model.countDocuments(filter),
        ])
        const page = Math.floor(skip / limit) + 1
        const totalPages = Math.ceil(total / limit)
        return { list: docs, total, page, pageSize: limit, totalPages }
    }

    async populateItems(items: any[], populates: IShrimpPopulate[], crudRegistry?: Map<string, any>): Promise<void> {
        for (const pop of populates) {
            // 优先用 getRelatedModel，其次用 crudRegistry（自动解析 relation）
            let relatedModel = this.getRelatedModel?.(pop.moduleKey)
            if (!relatedModel && crudRegistry) {
                const relatedCrud = crudRegistry.get(pop.moduleKey) as any
                relatedModel = relatedCrud?.model
            }
            if (!relatedModel) continue

            const allRefIds = new Set<string>()
            for (const item of items) {
                const val = (item as any)[pop.key]
                if (Array.isArray(val)) {
                    val.forEach((id: any) => { if (id != null) allRefIds.add(String(id)) })
                } else if (val != null) {
                    allRefIds.add(String(val))
                }
            }
            if (allRefIds.size === 0) continue
            const docs = await relatedModel.find({ _id: { $in: Array.from(allRefIds) } }).select(`${pop.labelKey} _id`)
            const labelMap = new Map(docs.map(doc => [String(doc._id), (doc as any)[pop.labelKey]]))
            for (const item of items) {
                const val = (item as any)[pop.key]
                if (Array.isArray(val)) {
                    (item as any)[`${pop.key}_label`] = val.map((id: any) => labelMap.get(String(id)) ?? null)
                } else if (val != null) {
                    (item as any)[`${pop.key}_label`] = labelMap.get(String(val)) ?? null
                }
            }
        }
    }

    async findOne(query?: any): Promise<T | null> {
        return await this.model.findOne(query || {}).lean() as T | null
    }

    async get(id: string): Promise<T | null> {
        return await this.model.findById(id).lean() as T | null;
    }
    async add(item: Omit<T, '_id'>): Promise<T> {
        return await this.model.create(item);
    }
    async edit(id: string, item: Partial<T>): Promise<T | null> {
        return await this.model.findByIdAndUpdate(id, item, { new: true });
    }
    async delete(id: string): Promise<boolean> {
        const result = await this.model.findByIdAndDelete(id);
        return !!result;
    }
    async clear(): Promise<boolean> {
        await this.model.deleteMany({});
        return true;
    }
}