package model

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"strings"
	"time"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"

	"spark-server/internal/module/square/entity"
	"spark-server/internal/pkg/errs"
)

// CreateBotPost inserts a bot RSS post and claims its source URL atomically.
func (m *Repo) CreateBotPost(ctx context.Context, post *entity.Post) error {
	if post == nil || post.ID <= 0 || post.UserID <= 0 {
		return errs.ErrInvalidArgument
	}
	url := strings.TrimSpace(post.SourceURL)
	if url == "" {
		return errs.ErrInvalidArgument
	}
	post.SourceURL = url
	if post.Source == 0 {
		post.Source = entity.SourceBotRSS
	}
	db, err := m.session(ctx)
	if err != nil {
		return err
	}
	row := postFrom(post)
	if row.CreatedAt.IsZero() {
		row.CreatedAt = time.Now()
	}
	hash := urlHash(url)
	return db.Transaction(func(tx *gorm.DB) error {
		link := BotLink{URLHash: hash, URL: url, PostID: post.ID, CreatedAt: row.CreatedAt}
		res := tx.Clauses(clause.OnConflict{DoNothing: true}).Create(&link)
		if res.Error != nil {
			return mapDBErr(res.Error)
		}
		if res.RowsAffected == 0 {
			return errs.ErrDuplicate
		}
		if err := tx.Create(row).Error; err != nil {
			return mapDBErr(err)
		}
		return nil
	})
}

// SoftDeleteExpiredBotPosts marks expired bot posts deleted; returns deleted rows for media GC.
func (m *Repo) SoftDeleteExpiredBotPosts(ctx context.Context, nowMS int64, limit int) ([]*entity.Post, error) {
	if limit <= 0 {
		limit = 100
	}
	if nowMS <= 0 {
		nowMS = time.Now().UnixMilli()
	}
	db, err := m.session(ctx)
	if err != nil {
		return nil, err
	}
	deadline := time.UnixMilli(nowMS)
	var rows []Post
	err = db.Transaction(func(tx *gorm.DB) error {
		q := tx.Where(
			"source = ? AND status = ? AND expires_at IS NOT NULL AND expires_at <= ?",
			entity.SourceBotRSS, entity.StatusNormal, deadline,
		).Order("expires_at ASC").Limit(limit)
		if err := q.Find(&rows).Error; err != nil {
			return mapDBErr(err)
		}
		if len(rows) == 0 {
			return nil
		}
		ids := make([]int64, 0, len(rows))
		for i := range rows {
			ids = append(ids, rows[i].ID)
		}
		res := tx.Model(&Post{}).Where("id IN ? AND status = ?", ids, entity.StatusNormal).
			Update("status", entity.StatusDeleted)
		if res.Error != nil {
			return mapDBErr(res.Error)
		}
		for i := range rows {
			rows[i].Status = int16(entity.StatusDeleted)
		}
		return nil
	})
	if err != nil {
		return nil, err
	}
	return collectPosts(rows), nil
}

func urlHash(url string) string {
	sum := sha256.Sum256([]byte(strings.TrimSpace(url)))
	return hex.EncodeToString(sum[:])
}