package cloudflare

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"sync"
	"time"
)

type Client struct {
	apiToken string
	zoneID   string
	client   *http.Client
	cache    *analyticsCache
}

type analyticsCache struct {
	mu      sync.RWMutex
	data    map[string]*cachedResult
	ttl     time.Duration
}

type cachedResult struct {
	result    *ZoneAnalytics
	expiresAt time.Time
}

func NewClient() *Client {
	return &Client{
		apiToken: os.Getenv("CLOUDFLARE_API_TOKEN"),
		zoneID:   os.Getenv("CLOUDFLARE_ZONE_ID"),
		client:   &http.Client{Timeout: 30 * time.Second},
		cache: &analyticsCache{
			data: make(map[string]*cachedResult),
			ttl:  5 * time.Minute,
		},
	}
}

func (c *Client) IsConfigured() bool {
	return c.apiToken != "" && c.zoneID != ""
}

type ZoneAnalytics struct {
	TotalRequests   int64           `json:"totalRequests"`
	TotalPageViews  int64           `json:"totalPageViews"`
	UniqueVisitors  int64           `json:"uniqueVisitors"`
	TotalBandwidth  int64           `json:"totalBandwidth"`
	Daily           []DailyStats    `json:"daily"`
	Browsers        []NamedCount    `json:"browsers"`
	OS              []NamedCount    `json:"os"`
	Devices         []NamedCount    `json:"devices"`
	Countries       []NamedCount    `json:"countries"`
	Paths           []PathStats     `json:"paths"`
}

type DailyStats struct {
	Date       string `json:"date"`
	Requests   int64  `json:"requests"`
	PageViews  int64  `json:"pageViews"`
	Visitors   int64  `json:"visitors"`
	Bandwidth  int64  `json:"bandwidth"`
}

type NamedCount struct {
	Name  string `json:"name"`
	Count int64  `json:"count"`
}

type PathStats struct {
	Path     string `json:"path"`
	Requests int64  `json:"requests"`
}

type graphqlRequest struct {
	Query     string         `json:"query"`
	Variables map[string]any `json:"variables,omitempty"`
}

type graphqlResponse struct {
	Data   json.RawMessage `json:"data"`
	Errors []struct {
		Message string `json:"message"`
	} `json:"errors,omitempty"`
}

func (c *Client) GetAnalytics(ctx context.Context, days int, hostname string) (*ZoneAnalytics, error) {
	if !c.IsConfigured() {
		return nil, fmt.Errorf("cloudflare not configured")
	}

	cacheKey := fmt.Sprintf("%s:%d:%s", c.zoneID, days, hostname)
	if cached := c.cache.get(cacheKey); cached != nil {
		return cached, nil
	}

	since := time.Now().AddDate(0, 0, -days).Format("2006-01-02")
	until := time.Now().Format("2006-01-02")

	result := &ZoneAnalytics{}

	dailyData, err := c.fetchDailyStats(ctx, since, until, hostname)
	if err != nil {
		return nil, err
	}
	result.Daily = dailyData

	for _, d := range dailyData {
		result.TotalRequests += d.Requests
		result.TotalPageViews += d.PageViews
		result.UniqueVisitors += d.Visitors
		result.TotalBandwidth += d.Bandwidth
	}

	browsers, _ := c.fetchGroupedStats(ctx, since, until, hostname, "clientRequestHTTPHost", "userAgentBrowser")
	result.Browsers = browsers

	osStats, _ := c.fetchGroupedStats(ctx, since, until, hostname, "clientRequestHTTPHost", "userAgentOS")
	result.OS = osStats

	devices, _ := c.fetchGroupedStats(ctx, since, until, hostname, "clientRequestHTTPHost", "deviceType")
	result.Devices = devices

	countries, _ := c.fetchGroupedStats(ctx, since, until, hostname, "clientRequestHTTPHost", "clientCountryName")
	result.Countries = countries

	paths, _ := c.fetchPathStats(ctx, since, until, hostname)
	result.Paths = paths

	c.cache.set(cacheKey, result)

	return result, nil
}

func (c *Client) fetchDailyStats(ctx context.Context, since, until, hostname string) ([]DailyStats, error) {
	query := `
		query ($zoneTag: String!, $since: Date!, $until: Date!, $hostname: String!) {
			viewer {
				zones(filter: { zoneTag: $zoneTag }) {
					httpRequests1dGroups(
						filter: { date_geq: $since, date_leq: $until, clientRequestHTTPHost: $hostname }
						orderBy: [date_ASC]
						limit: 100
					) {
						dimensions {
							date
						}
						sum {
							requests
							pageViews
							bytes
						}
						uniq {
							uniques
						}
					}
				}
			}
		}
	`

	vars := map[string]any{
		"zoneTag":  c.zoneID,
		"since":    since,
		"until":    until,
		"hostname": hostname,
	}

	resp, err := c.doQuery(ctx, query, vars)
	if err != nil {
		return nil, err
	}

	var data struct {
		Viewer struct {
			Zones []struct {
				HttpRequests1dGroups []struct {
					Dimensions struct {
						Date string `json:"date"`
					} `json:"dimensions"`
					Sum struct {
						Requests  int64 `json:"requests"`
						PageViews int64 `json:"pageViews"`
						Bytes     int64 `json:"bytes"`
					} `json:"sum"`
					Uniq struct {
						Uniques int64 `json:"uniques"`
					} `json:"uniq"`
				} `json:"httpRequests1dGroups"`
			} `json:"zones"`
		} `json:"viewer"`
	}

	if err := json.Unmarshal(resp, &data); err != nil {
		return nil, fmt.Errorf("parse response: %w", err)
	}

	var results []DailyStats
	if len(data.Viewer.Zones) > 0 {
		for _, g := range data.Viewer.Zones[0].HttpRequests1dGroups {
			results = append(results, DailyStats{
				Date:      g.Dimensions.Date,
				Requests:  g.Sum.Requests,
				PageViews: g.Sum.PageViews,
				Visitors:  g.Uniq.Uniques,
				Bandwidth: g.Sum.Bytes,
			})
		}
	}

	return results, nil
}

func (c *Client) fetchGroupedStats(ctx context.Context, since, until, hostname, hostField, groupBy string) ([]NamedCount, error) {
	query := fmt.Sprintf(`
		query ($zoneTag: String!, $since: Date!, $until: Date!, $hostname: String!) {
			viewer {
				zones(filter: { zoneTag: $zoneTag }) {
					httpRequests1dGroups(
						filter: { date_geq: $since, date_leq: $until, %s: $hostname }
						orderBy: [sum_requests_DESC]
						limit: 10
					) {
						dimensions {
							%s
						}
						sum {
							requests
						}
					}
				}
			}
		}
	`, hostField, groupBy)

	vars := map[string]any{
		"zoneTag":  c.zoneID,
		"since":    since,
		"until":    until,
		"hostname": hostname,
	}

	resp, err := c.doQuery(ctx, query, vars)
	if err != nil {
		return nil, err
	}

	var data struct {
		Viewer struct {
			Zones []struct {
				HttpRequests1dGroups []struct {
					Dimensions map[string]string `json:"dimensions"`
					Sum        struct {
						Requests int64 `json:"requests"`
					} `json:"sum"`
				} `json:"httpRequests1dGroups"`
			} `json:"zones"`
		} `json:"viewer"`
	}

	if err := json.Unmarshal(resp, &data); err != nil {
		return nil, fmt.Errorf("parse response: %w", err)
	}

	var results []NamedCount
	if len(data.Viewer.Zones) > 0 {
		for _, g := range data.Viewer.Zones[0].HttpRequests1dGroups {
			name := g.Dimensions[groupBy]
			if name == "" {
				name = "Unknown"
			}
			results = append(results, NamedCount{
				Name:  name,
				Count: g.Sum.Requests,
			})
		}
	}

	return results, nil
}

func (c *Client) fetchPathStats(ctx context.Context, since, until, hostname string) ([]PathStats, error) {
	query := `
		query ($zoneTag: String!, $since: Date!, $until: Date!, $hostname: String!) {
			viewer {
				zones(filter: { zoneTag: $zoneTag }) {
					httpRequests1dGroups(
						filter: { date_geq: $since, date_leq: $until, clientRequestHTTPHost: $hostname }
						orderBy: [sum_requests_DESC]
						limit: 20
					) {
						dimensions {
							clientRequestPath
						}
						sum {
							requests
						}
					}
				}
			}
		}
	`

	vars := map[string]any{
		"zoneTag":  c.zoneID,
		"since":    since,
		"until":    until,
		"hostname": hostname,
	}

	resp, err := c.doQuery(ctx, query, vars)
	if err != nil {
		return nil, err
	}

	var data struct {
		Viewer struct {
			Zones []struct {
				HttpRequests1dGroups []struct {
					Dimensions struct {
						Path string `json:"clientRequestPath"`
					} `json:"dimensions"`
					Sum struct {
						Requests int64 `json:"requests"`
					} `json:"sum"`
				} `json:"httpRequests1dGroups"`
			} `json:"zones"`
		} `json:"viewer"`
	}

	if err := json.Unmarshal(resp, &data); err != nil {
		return nil, fmt.Errorf("parse response: %w", err)
	}

	var results []PathStats
	if len(data.Viewer.Zones) > 0 {
		for _, g := range data.Viewer.Zones[0].HttpRequests1dGroups {
			results = append(results, PathStats{
				Path:     g.Dimensions.Path,
				Requests: g.Sum.Requests,
			})
		}
	}

	return results, nil
}

func (c *Client) doQuery(ctx context.Context, query string, vars map[string]any) (json.RawMessage, error) {
	reqBody := graphqlRequest{
		Query:     query,
		Variables: vars,
	}

	body, err := json.Marshal(reqBody)
	if err != nil {
		return nil, err
	}

	req, err := http.NewRequestWithContext(ctx, "POST", "https://api.cloudflare.com/client/v4/graphql", bytes.NewReader(body))
	if err != nil {
		return nil, err
	}

	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "Bearer "+c.apiToken)

	resp, err := c.client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	respBody, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("cloudflare API error: %s", string(respBody))
	}

	var gqlResp graphqlResponse
	if err := json.Unmarshal(respBody, &gqlResp); err != nil {
		return nil, err
	}

	if len(gqlResp.Errors) > 0 {
		return nil, fmt.Errorf("graphql error: %s", gqlResp.Errors[0].Message)
	}

	return gqlResp.Data, nil
}

func (c *analyticsCache) get(key string) *ZoneAnalytics {
	c.mu.RLock()
	defer c.mu.RUnlock()

	if cached, ok := c.data[key]; ok && time.Now().Before(cached.expiresAt) {
		return cached.result
	}
	return nil
}

func (c *analyticsCache) set(key string, result *ZoneAnalytics) {
	c.mu.Lock()
	defer c.mu.Unlock()

	c.data[key] = &cachedResult{
		result:    result,
		expiresAt: time.Now().Add(c.ttl),
	}
}

func (c *Client) PurgeURLs(ctx context.Context, urls []string) error {
	if !c.IsConfigured() || len(urls) == 0 {
		return nil
	}

	body, err := json.Marshal(map[string][]string{"files": urls})
	if err != nil {
		return err
	}

	req, err := http.NewRequestWithContext(ctx, "POST",
		fmt.Sprintf("https://api.cloudflare.com/client/v4/zones/%s/purge_cache", c.zoneID),
		bytes.NewReader(body))
	if err != nil {
		return err
	}

	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "Bearer "+c.apiToken)

	resp, err := c.client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		respBody, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("cloudflare purge failed: %s", string(respBody))
	}

	return nil
}