package memory

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

	"github.com/yourname/cyrene-ai/ai-core/internal/model"
)

// Client 记忆服务 HTTP 客户端
// ai-core 通过此客户端调用独立的 memory-service
type Client struct {
	baseURL    string
	httpClient *http.Client
}

// NewClient 创建记忆服务客户端
func NewClient(baseURL string) *Client {
	return &Client{
		baseURL: baseURL,
		httpClient: &http.Client{
			Timeout: 15 * time.Second,
		},
	}
}

// Ping 检查记忆服务是否可用
func (c *Client) Ping(ctx context.Context) error {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, c.baseURL+"/api/v1/health", nil)
	if err != nil {
		return err
	}
	resp, err := c.httpClient.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("记忆服务健康检查失败: %d", resp.StatusCode)
	}
	return nil
}

// Save 保存记忆
func (c *Client) Save(ctx context.Context, entry *model.MemoryEntry) error {
	body, _ := json.Marshal(map[string]interface{}{
		"user_id":    entry.UserID,
		"content":    entry.Content,
		"summary":    entry.Summary,
		"category":   string(entry.Category),
		"priority":   int(entry.Priority),
		"importance": entry.Importance,
		"keywords":   entry.Keywords,
		"session_id": entry.SessionID,
		"source":     entry.Source,
	})

	resp, err := c.doRequest(ctx, http.MethodPost, c.baseURL+"/api/v1/memories", body)
	if err != nil {
		return fmt.Errorf("保存记忆失败: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 300 {
		respBody, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("保存记忆失败 (%d): %s", resp.StatusCode, string(respBody))
	}

	// 解析返回以获取 ID 和 CreatedAt
	var result struct {
		Memory *model.MemoryEntry `json:"memory"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err == nil && result.Memory != nil {
		entry.ID = result.Memory.ID
		entry.CreatedAt = result.Memory.CreatedAt
	}

	return nil
}

// Query 按条件查询记忆
func (c *Client) Query(ctx context.Context, q model.MemoryQuery) ([]model.MemoryEntry, error) {
	url := fmt.Sprintf("%s/api/v1/memories?user_id=%s", c.baseURL, q.UserID)
	if q.Category != "" {
		url += "&category=" + string(q.Category)
	}
	if q.MinImportance > 0 {
		url += fmt.Sprintf("&min_importance=%d", q.MinImportance)
	}
	if q.Limit > 0 {
		url += fmt.Sprintf("&limit=%d", q.Limit)
	}

	resp, err := c.doRequest(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, fmt.Errorf("查询记忆失败: %w", err)
	}
	defer resp.Body.Close()

	var result struct {
		Memories []model.MemoryEntry `json:"memories"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return nil, fmt.Errorf("解析查询结果失败: %w", err)
	}
	return result.Memories, nil
}

// QueryByText 语义查询（POST /api/v1/memories/query）
func (c *Client) QueryByText(ctx context.Context, userID, queryText, category string, minImportance, limit int) ([]model.MemoryEntry, error) {
	body, _ := json.Marshal(map[string]interface{}{
		"user_id":        userID,
		"query_text":     queryText,
		"category":       category,
		"min_importance": minImportance,
		"limit":          limit,
	})

	resp, err := c.doRequest(ctx, http.MethodPost, c.baseURL+"/api/v1/memories/query", body)
	if err != nil {
		return nil, fmt.Errorf("语义查询失败: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 300 {
		respBody, _ := io.ReadAll(resp.Body)
		return nil, fmt.Errorf("语义查询失败 (%d): %s", resp.StatusCode, string(respBody))
	}

	var result struct {
		Memories []model.MemoryEntry `json:"memories"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return nil, fmt.Errorf("解析查询结果失败: %w", err)
	}
	return result.Memories, nil
}

// GetByID 根据ID获取记忆
func (c *Client) GetByID(ctx context.Context, id string) (*model.MemoryEntry, error) {
	resp, err := c.doRequest(ctx, http.MethodGet, c.baseURL+"/api/v1/memories/"+id, nil)
	if err != nil {
		return nil, fmt.Errorf("获取记忆失败: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusNotFound {
		return nil, nil
	}
	if resp.StatusCode >= 300 {
		respBody, _ := io.ReadAll(resp.Body)
		return nil, fmt.Errorf("获取记忆失败 (%d): %s", resp.StatusCode, string(respBody))
	}

	var result struct {
		Memory model.MemoryEntry `json:"memory"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return nil, fmt.Errorf("解析获取结果失败: %w", err)
	}
	return &result.Memory, nil
}

// Delete 删除记忆
func (c *Client) Delete(ctx context.Context, id string) error {
	resp, err := c.doRequest(ctx, http.MethodDelete, c.baseURL+"/api/v1/memories/"+id, nil)
	if err != nil {
		return fmt.Errorf("删除记忆失败: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 300 {
		respBody, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("删除记忆失败 (%d): %s", resp.StatusCode, string(respBody))
	}
	return nil
}

// GetMemoriesByCategory 按分类获取记忆
func (c *Client) GetMemoriesByCategory(ctx context.Context, userID string, category model.MemoryCategory) ([]model.MemoryEntry, error) {
	return c.Query(ctx, model.MemoryQuery{
		UserID:   userID,
		Category: category,
		Limit:    50,
	})
}

// ConsolidateMemories 合并相似记忆
func (c *Client) ConsolidateMemories(ctx context.Context, userID string) (int, error) {
	body, _ := json.Marshal(map[string]interface{}{
		"user_id": userID,
	})

	resp, err := c.doRequest(ctx, http.MethodPost, c.baseURL+"/api/v1/memories/consolidate", body)
	if err != nil {
		return 0, fmt.Errorf("合并记忆失败: %w", err)
	}
	defer resp.Body.Close()

	var result struct {
		Merged int `json:"merged"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return 0, fmt.Errorf("解析合并结果失败: %w", err)
	}
	return result.Merged, nil
}

// DecayMemories 衰减旧记忆
func (c *Client) DecayMemories(ctx context.Context, userID string) (int, int, error) {
	body, _ := json.Marshal(map[string]interface{}{
		"user_id": userID,
	})

	resp, err := c.doRequest(ctx, http.MethodPost, c.baseURL+"/api/v1/memories/decay", body)
	if err != nil {
		return 0, 0, fmt.Errorf("衰减记忆失败: %w", err)
	}
	defer resp.Body.Close()

	var result struct {
		Decayed int `json:"decayed"`
		Deleted int `json:"deleted"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return 0, 0, fmt.Errorf("解析衰减结果失败: %w", err)
	}
	return result.Decayed, result.Deleted, nil
}

// GetCategories 获取用户类别统计
func (c *Client) GetCategories(ctx context.Context, userID string) (map[string]int, error) {
	url := fmt.Sprintf("%s/api/v1/memories/categories?user_id=%s", c.baseURL, userID)
	resp, err := c.doRequest(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, fmt.Errorf("获取类别统计失败: %w", err)
	}
	defer resp.Body.Close()

	var result struct {
		Categories map[string]int `json:"categories"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return nil, fmt.Errorf("解析类别统计失败: %w", err)
	}
	return result.Categories, nil
}

// SaveThinkingLog 持久化自主思考日志到 memory-service
func (c *Client) SaveThinkingLog(ctx context.Context, userID, content, toolCalls string, toolCallCount, contentLength int) error {
	body, _ := json.Marshal(map[string]interface{}{
		"user_id":         userID,
		"content":         content,
		"tool_calls":      toolCalls,
		"tool_call_count": toolCallCount,
		"content_length":  contentLength,
	})

	resp, err := c.doRequest(ctx, http.MethodPost, c.baseURL+"/api/v1/thinking", body)
	if err != nil {
		return fmt.Errorf("保存思考日志失败: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 300 {
		respBody, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("保存思考日志失败 (%d): %s", resp.StatusCode, string(respBody))
	}

	return nil
}

// IsReady 检查记忆服务是否就绪
func (c *Client) IsReady() bool {
	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
	defer cancel()
	return c.Ping(ctx) == nil
}

// doRequest 内部 HTTP 请求辅助方法
func (c *Client) doRequest(ctx context.Context, method, url string, body []byte) (*http.Response, error) {
	var reqBody io.Reader
	if body != nil {
		reqBody = bytes.NewReader(body)
	}

	req, err := http.NewRequestWithContext(ctx, method, url, reqBody)
	if err != nil {
		return nil, err
	}

	if body != nil {
		req.Header.Set("Content-Type", "application/json")
	}

	resp, err := c.httpClient.Do(req)
	if err != nil {
		log.Printf("[memory-client] HTTP 请求失败 %s %s: %v", method, url, err)
		return nil, err
	}

	return resp, nil
}