package gorse

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"time"

	gorseio "github.com/gorse-io/gorse-go"
)

// FeedbackType 反馈类型
type FeedbackType string

const (
	FeedbackTypeLike     FeedbackType = "like"     // 点赞
	FeedbackTypeStar     FeedbackType = "star"     // 收藏
	FeedbackTypeComment  FeedbackType = "comment"  // 评论
	FeedbackTypeRead     FeedbackType = "read"     // 浏览
)

// Score 非个性化推荐返回的评分项
type Score struct {
	Id    string  `json:"Id"`
	Score float64 `json:"Score"`
}

// Client Gorse客户端接口
type Client interface {
	// InsertFeedback 插入用户反馈
	InsertFeedback(ctx context.Context, feedbackType FeedbackType, userID, itemID string) error
	// DeleteFeedback 删除用户反馈
	DeleteFeedback(ctx context.Context, feedbackType FeedbackType, userID, itemID string) error
	// GetRecommend 获取个性化推荐列表
	GetRecommend(ctx context.Context, userID string, n int, offset int) ([]string, error)
	// GetNonPersonalized 获取非个性化推荐（通过名称）
	GetNonPersonalized(ctx context.Context, name string, n int, offset int, userID string) ([]string, error)
	// UpsertItem 插入或更新物品（无embedding）
	UpsertItem(ctx context.Context, itemID string, categories []string, comment string) error
	// UpsertItemWithEmbedding 插入或更新物品（带embedding）
	UpsertItemWithEmbedding(ctx context.Context, itemID string, categories []string, comment string, textToEmbed string) error
	// DeleteItem 删除物品
	DeleteItem(ctx context.Context, itemID string) error
	// UpsertUser 插入或更新用户
	UpsertUser(ctx context.Context, userID string, labels map[string]any) error
	// IsEnabled 检查是否启用
	IsEnabled() bool
}

// client Gorse客户端实现
type client struct {
	config     Config
	gorse      *gorseio.GorseClient
	httpClient *http.Client
}

// NewClient 创建新的Gorse客户端
func NewClient(cfg Config) Client {
	if !cfg.Enabled {
		return &noopClient{}
	}

	gorse := gorseio.NewGorseClient(cfg.Address, cfg.APIKey)
	return &client{
		config: cfg,
		gorse:  gorse,
		httpClient: &http.Client{
			Timeout: 10 * time.Second,
		},
	}
}

// IsEnabled 检查是否启用
func (c *client) IsEnabled() bool {
	return c.config.Enabled
}

// InsertFeedback 插入用户反馈
func (c *client) InsertFeedback(ctx context.Context, feedbackType FeedbackType, userID, itemID string) error {
	if !c.config.Enabled {
		return nil
	}

	_, err := c.gorse.InsertFeedback(ctx, []gorseio.Feedback{
		{
			FeedbackType: string(feedbackType),
			UserId:       userID,
			ItemId:       itemID,
			Timestamp:    time.Now().UTC().Truncate(time.Second),
		},
	})
	return err
}

// DeleteFeedback 删除用户反馈
func (c *client) DeleteFeedback(ctx context.Context, feedbackType FeedbackType, userID, itemID string) error {
	if !c.config.Enabled {
		return nil
	}

	_, err := c.gorse.DeleteFeedback(ctx, string(feedbackType), userID, itemID)
	return err
}

// GetRecommend 获取个性化推荐列表
func (c *client) GetRecommend(ctx context.Context, userID string, n int, offset int) ([]string, error) {
	if !c.config.Enabled {
		return nil, nil
	}

	result, err := c.gorse.GetRecommend(ctx, userID, "", n, offset)
	if err != nil {
		return nil, err
	}

	return result, nil
}

// GetNonPersonalized 获取非个性化推荐
// name: 推荐器名称，如 "most_liked_weekly"
// n: 返回数量
// offset: 偏移量
// userID: 可选，用于排除用户已读物品
func (c *client) GetNonPersonalized(ctx context.Context, name string, n int, offset int, userID string) ([]string, error) {
	if !c.config.Enabled {
		return nil, nil
	}

	// 构建URL
	url := fmt.Sprintf("%s/api/non-personalized/%s?n=%d&offset=%d", c.config.Address, name, n, offset)
	if userID != "" {
		url += fmt.Sprintf("&user-id=%s", userID)
	}

	// 创建请求
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}

	// 设置API Key
	if c.config.APIKey != "" {
		req.Header.Set("X-API-Key", c.config.APIKey)
	}

	// 发送请求
	resp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("failed to send request: %w", err)
	}
	defer resp.Body.Close()

	// 读取响应
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("failed to read response: %w", err)
	}

	if resp.StatusCode >= 400 {
		return nil, fmt.Errorf("gorse api error: status=%d, body=%s", resp.StatusCode, string(body))
	}

	// 解析响应
	var scores []Score
	if err := json.Unmarshal(body, &scores); err != nil {
		return nil, fmt.Errorf("failed to unmarshal response: %w", err)
	}

	// 提取ID
	ids := make([]string, len(scores))
	for i, score := range scores {
		ids[i] = score.Id
	}

	return ids, nil
}

// UpsertItem 插入或更新物品
func (c *client) UpsertItem(ctx context.Context, itemID string, categories []string, comment string) error {
	if !c.config.Enabled {
		return nil
	}

	_, err := c.gorse.InsertItem(ctx, gorseio.Item{
		ItemId:     itemID,
		IsHidden:   false,
		Categories: categories,
		Comment:    comment,
		Timestamp:  time.Now().UTC().Truncate(time.Second),
	})
	return err
}

// UpsertItemWithEmbedding 插入或更新物品（带embedding）
func (c *client) UpsertItemWithEmbedding(ctx context.Context, itemID string, categories []string, comment string, textToEmbed string) error {
	if !c.config.Enabled {
		return nil
	}

	// 生成embedding
	var embedding []float64
	if textToEmbed != "" {
		var err error
		embedding, err = GetEmbedding(textToEmbed)
		if err != nil {
			log.Printf("[WARN] Failed to get embedding for item %s: %v, using zero vector", itemID, err)
			embedding = make([]float64, 1024)
		}
	} else {
		embedding = make([]float64, 1024)
	}

	_, err := c.gorse.InsertItem(ctx, gorseio.Item{
		ItemId:     itemID,
		IsHidden:   false,
		Categories: categories,
		Comment:    comment,
		Timestamp:  time.Now().UTC().Truncate(time.Second),
		Labels: map[string]any{
			"embedding": embedding,
		},
	})
	return err
}

// DeleteItem 删除物品
func (c *client) DeleteItem(ctx context.Context, itemID string) error {
	if !c.config.Enabled {
		return nil
	}

	_, err := c.gorse.DeleteItem(ctx, itemID)
	return err
}

// UpsertUser 插入或更新用户
func (c *client) UpsertUser(ctx context.Context, userID string, labels map[string]any) error {
	if !c.config.Enabled {
		return nil
	}

	_, err := c.gorse.InsertUser(ctx, gorseio.User{
		UserId: userID,
		Labels: labels,
	})
	return err
}

// noopClient 空操作客户端（用于未启用推荐功能时）
type noopClient struct{}

func (c *noopClient) IsEnabled() bool { return false }
func (c *noopClient) InsertFeedback(ctx context.Context, feedbackType FeedbackType, userID, itemID string) error {
	return nil
}
func (c *noopClient) DeleteFeedback(ctx context.Context, feedbackType FeedbackType, userID, itemID string) error {
	return nil
}
func (c *noopClient) GetRecommend(ctx context.Context, userID string, n int, offset int) ([]string, error) {
	return nil, nil
}
func (c *noopClient) GetNonPersonalized(ctx context.Context, name string, n int, offset int, userID string) ([]string, error) {
	return nil, nil
}
func (c *noopClient) UpsertItem(ctx context.Context, itemID string, categories []string, comment string) error {
	return nil
}
func (c *noopClient) UpsertItemWithEmbedding(ctx context.Context, itemID string, categories []string, comment string, textToEmbed string) error {
	return nil
}
func (c *noopClient) DeleteItem(ctx context.Context, itemID string) error { return nil }
func (c *noopClient) UpsertUser(ctx context.Context, userID string, labels map[string]any) error {
	return nil
}

// 确保实现了接口
var _ Client = (*client)(nil)
var _ Client = (*noopClient)(nil)

// log 用于内部日志
func init() {
	log.SetFlags(log.LstdFlags | log.Lshortfile)
}