package logx

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

	"git.liteyuki.org/LiteyukiStudio/folium/osx"
	"github.com/prometheus/client_golang/prometheus"
)

type ConsoleCollector struct{}

func NewConsoleCollector() *ConsoleCollector { return &ConsoleCollector{} }

func (c *ConsoleCollector) Collect(ctx context.Context, e Entry) error {
	// 简单输出 JSON 行，供外部 log collector（Fluent/FluentBit）抓取
	b, _ := json.Marshal(e)
	fmt.Fprintln(os.Stdout, string(b))
	return nil
}
func (c *ConsoleCollector) Close() error { return nil }

// LokiCollector：把日志推送到 Loki push API（基本实现）
type LokiCollector struct {
	url    string
	client *http.Client
	labels string // e.g. `{job="myapp"}`
}

func NewLokiCollector(collectorURL string, labels map[string]string) *LokiCollector {
	// 构建 labels 字符串
	lbl := "{"
	first := true
	for k, v := range labels {
		if !first {
			lbl += ","
		}
		lbl += fmt.Sprintf("%s=\"%s\"", k, v)
		first = false
	}
	lbl += "}"
	return &LokiCollector{
		url:    collectorURL,
		client: &http.Client{Timeout: 5 * time.Second},
		labels: lbl,
	}
}

type lokiStream struct {
	Stream map[string]string `json:"stream"`
	Values [][2]string       `json:"values"`
}
type lokiPush struct {
	Streams []lokiStream `json:"streams"`
}

func (c *LokiCollector) Collect(ctx context.Context, e Entry) error {
	// Loki requires timestamp in nanoseconds as string
	ts := fmt.Sprintf("%d", e.Time.UnixNano())
	lineB, _ := json.Marshal(e)
	stream := lokiStream{
		Stream: map[string]string{"level": string(e.Level)},
		Values: [][2]string{{ts, string(lineB)}},
	}
	push := lokiPush{Streams: []lokiStream{stream}}
	body, _ := json.Marshal(push)
	req, _ := http.NewRequestWithContext(ctx, "POST", c.url+"/loki/api/v1/push", bytes.NewBuffer(body))
	req.Header.Set("Content-Type", "application/json")
	resp, err := c.client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 300 {
		return fmt.Errorf("loki push status %d", resp.StatusCode)
	}
	return nil
}
func (c *LokiCollector) Close() error { return nil }

// ESCollector：把日志写入 Elasticsearch 简单实现（使用 index API）
type ESCollector struct {
	url    string // e.g. http://es:9200
	index  string // index name
	client *http.Client
	auth   *basicAuth // optional
}

type basicAuth struct {
	user string
	pass string
}

func NewESCollector(url, index string, authUser, authPass string) *ESCollector {
	var auth *basicAuth
	if authUser != "" {
		auth = &basicAuth{user: authUser, pass: authPass}
	}
	return &ESCollector{
		url:    url,
		index:  index,
		client: &http.Client{Timeout: 5 * time.Second},
		auth:   auth,
	}
}

func (c *ESCollector) Collect(ctx context.Context, e Entry) error {
	b, _ := json.Marshal(e)
	endpoint := fmt.Sprintf("%s/%s/_doc", c.url, c.index)
	req, _ := http.NewRequestWithContext(ctx, "POST", endpoint, bytes.NewBuffer(b))
	req.Header.Set("Content-Type", "application/json")
	if c.auth != nil {
		req.SetBasicAuth(c.auth.user, c.auth.pass)
	}
	resp, err := c.client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 300 {
		return fmt.Errorf("es index status %d", resp.StatusCode)
	}
	return nil
}
func (c *ESCollector) Close() error { return nil }

// PromCollector：记录日志计数到 Prometheus（便于监控日志量）
type PromCollector struct {
	counter *prometheus.CounterVec
}

func NewPromCollector(namespace string) *PromCollector {
	cv := prometheus.NewCounterVec(prometheus.CounterOpts{
		Namespace: namespace,
		Name:      "app_logs_total",
		Help:      "Total application logs by level",
	}, []string{"level"})
	// 忽略重复注册错误（如果已存在，使用已注册的）
	_ = prometheus.Register(cv)
	return &PromCollector{
		counter: cv,
	}
}

func (p *PromCollector) Collect(ctx context.Context, e Entry) error {
	p.counter.WithLabelValues(string(e.Level)).Inc()
	return nil
}
func (p *PromCollector) Close() error { return nil }

// LoadCollectorsFromEnv 根据环境变量 LOG_COLLECTORS 加载对应的 collectors
func LoadCollectorsFromEnv() []Collector {
	collectors := osx.GetEnv("LOG_COLLECTORS", "")
	var result []Collector
	if collectors == "" {
		return result
	}
	types := bytes.Split([]byte(collectors), []byte(","))
	for _, t := range types {
		switch string(bytes.TrimSpace(t)) {
		case "console":
			result = append(result, NewConsoleCollector())
		case "loki":
			lokiURL := osx.GetEnv("LOKI_URL", "http://localhost:3100")
			labels := map[string]string{
				"job": osx.GetEnv("LOKI_JOB", "myapp"),
			}
			result = append(result, NewLokiCollector(lokiURL, labels))
		case "elasticsearch":
			esURL := osx.GetEnv("ES_URL", "http://localhost:9200")
			esIndex := osx.GetEnv("ES_INDEX", "app-logs")
			esUser := osx.GetEnv("ES_USER", "")
			esPass := osx.GetEnv("ES_PASS", "")
			result = append(result, NewESCollector(esURL, esIndex, esUser, esPass))
		case "prometheus":
			namespace := osx.GetEnv("PROM_NAMESPACE", "myapp")
			result = append(result, NewPromCollector(namespace))
			// 可扩展更多 collector 类型
		}
	}
	return result
}