package api

import (
	"encoding/json"
	"io"
	"net/http"
	"strconv"
	"strings"
	"time"

	"proxyrotator/internal/config"
	"proxyrotator/internal/importer"
	"proxyrotator/internal/model"
	"proxyrotator/internal/security"
	"proxyrotator/internal/selector"
	"proxyrotator/internal/store"
	"proxyrotator/internal/tester"
)

// Handlers API 处理器集合
type Handlers struct {
	store    store.ProxyStore
	importer *importer.Importer
	tester   *tester.HTTPTester
	selector *selector.Selector
	cfg      *config.Config
}

// NewHandlers 创建处理器
func NewHandlers(
	store store.ProxyStore,
	importer *importer.Importer,
	tester *tester.HTTPTester,
	selector *selector.Selector,
	cfg *config.Config,
) *Handlers {
	return &Handlers{
		store:    store,
		importer: importer,
		tester:   tester,
		selector: selector,
		cfg:      cfg,
	}
}

// HandleImportText 文本导入处理器
// POST /v1/proxies/import/text
func (h *Handlers) HandleImportText(w http.ResponseWriter, r *http.Request) {
	var req model.ImportTextRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", "invalid JSON body")
		return
	}

	if req.Text == "" {
		writeError(w, http.StatusBadRequest, "bad_request", "text is required")
		return
	}

	input := model.ImportInput{
		Group:        coalesce(req.Group, "default"),
		Tags:         req.Tags,
		ProtocolHint: req.ProtocolHint,
	}

	proxies, invalid := h.importer.ParseText(r.Context(), input, req.Text)

	imported, duplicated := 0, 0
	if len(proxies) > 0 {
		var err error
		imported, duplicated, err = h.store.UpsertMany(r.Context(), proxies)
		if err != nil {
			writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
			return
		}
	}

	writeJSON(w, http.StatusOK, model.ImportResult{
		Imported:     imported,
		Duplicated:   duplicated,
		Invalid:      len(invalid),
		InvalidItems: invalid,
	})
}

// HandleImportFile 文件上传导入处理器
// POST /v1/proxies/import/file
func (h *Handlers) HandleImportFile(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseMultipartForm(10 << 20); err != nil { // 10MB 限制
		writeError(w, http.StatusBadRequest, "bad_request", "failed to parse multipart form")
		return
	}

	file, header, err := r.FormFile("file")
	if err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", "file is required")
		return
	}
	defer file.Close()

	group := coalesce(r.FormValue("group"), "default")
	tagsStr := r.FormValue("tags")
	var tags []string
	if tagsStr != "" {
		tags = strings.Split(tagsStr, ",")
		for i := range tags {
			tags[i] = strings.TrimSpace(tags[i])
		}
	}

	input := model.ImportInput{
		Group:        group,
		Tags:         tags,
		ProtocolHint: r.FormValue("protocol_hint"),
	}

	// 读取文件内容
	content, err := io.ReadAll(file)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal_error", "failed to read file")
		return
	}

	var proxies []model.Proxy
	var invalid []model.InvalidLine

	// 根据文件类型解析
	fileType := r.FormValue("type")
	if fileType == "" {
		// 根据文件名推断
		if strings.HasSuffix(strings.ToLower(header.Filename), ".csv") {
			fileType = "csv"
		} else {
			fileType = "txt"
		}
	}

	if fileType == "csv" {
		proxies, invalid = h.importer.ParseCSV(r.Context(), input, strings.NewReader(string(content)))
	} else {
		proxies, invalid = h.importer.ParseText(r.Context(), input, string(content))
	}

	imported, duplicated := 0, 0
	if len(proxies) > 0 {
		imported, duplicated, err = h.store.UpsertMany(r.Context(), proxies)
		if err != nil {
			writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
			return
		}
	}

	writeJSON(w, http.StatusOK, model.ImportResult{
		Imported:     imported,
		Duplicated:   duplicated,
		Invalid:      len(invalid),
		InvalidItems: invalid,
	})
}

// HandleTest 测试代理处理器
// POST /v1/proxies/test
func (h *Handlers) HandleTest(w http.ResponseWriter, r *http.Request) {
	var req model.TestRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", "invalid JSON body")
		return
	}

	// SSRF 防护
	if req.TestSpec.URL == "" {
		writeError(w, http.StatusBadRequest, "bad_request", "test_spec.url is required")
		return
	}
	if err := security.ValidateTestURL(req.TestSpec.URL); err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", err.Error())
		return
	}

	// 限制并发数
	concurrency := req.Concurrency
	if concurrency <= 0 {
		concurrency = 50
	}
	if concurrency > h.cfg.MaxConcurrency {
		concurrency = h.cfg.MaxConcurrency
	}

	// 限制测试数量
	limit := req.Filter.Limit
	if limit <= 0 || limit > h.cfg.MaxTestLimit {
		limit = h.cfg.MaxTestLimit
	}

	// 构建查询条件
	var statusIn []model.ProxyStatus
	for _, s := range req.Filter.Status {
		statusIn = append(statusIn, model.ProxyStatus(s))
	}
	if len(statusIn) == 0 {
		statusIn = []model.ProxyStatus{model.StatusUnknown, model.StatusAlive}
	}

	proxies, err := h.store.List(r.Context(), model.ProxyQuery{
		Group:       coalesce(req.Group, "default"),
		TagsAny:     req.Filter.TagsAny,
		StatusIn:    statusIn,
		OnlyEnabled: true,
		Limit:       limit,
	})
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
		return
	}

	if len(proxies) == 0 {
		writeJSON(w, http.StatusOK, model.TestBatchResult{
			Summary: model.TestSummary{},
			Results: []model.TestResult{},
		})
		return
	}

	// 构建测试规格
	timeout := time.Duration(req.TestSpec.TimeoutMs) * time.Millisecond
	if timeout <= 0 {
		timeout = 5 * time.Second
	}

	spec := model.TestSpec{
		URL:            req.TestSpec.URL,
		Method:         coalesce(req.TestSpec.Method, "GET"),
		Timeout:        timeout,
		ExpectStatus:   req.TestSpec.ExpectStatus,
		ExpectContains: req.TestSpec.ExpectContains,
	}

	// 执行测试
	results := h.tester.TestBatch(r.Context(), proxies, spec, concurrency)

	// 统计结果
	summary := model.TestSummary{Tested: len(results)}
	for _, result := range results {
		if result.OK {
			summary.Alive++
		} else {
			summary.Dead++
		}

		// 更新数据库
		if req.UpdateStore {
			now := result.CheckedAt
			if result.OK {
				status := model.StatusAlive
				_ = h.store.UpdateHealth(r.Context(), result.ProxyID, model.HealthPatch{
					Status:     &status,
					ScoreDelta: 1,
					SuccessInc: 1,
					LatencyMs:  &result.LatencyMs,
					CheckedAt:  &now,
				})
			} else {
				status := model.StatusDead
				_ = h.store.UpdateHealth(r.Context(), result.ProxyID, model.HealthPatch{
					Status:     &status,
					ScoreDelta: -3,
					FailInc:    1,
					CheckedAt:  &now,
				})
			}
		}

		// 写入测试日志
		if req.WriteLog {
			_ = h.store.InsertTestLog(r.Context(), result, req.TestSpec.URL)
		}
	}

	writeJSON(w, http.StatusOK, model.TestBatchResult{
		Summary: summary,
		Results: results,
	})
}

// HandleNext 获取下一个可用代理
// GET /v1/proxies/next
func (h *Handlers) HandleNext(w http.ResponseWriter, r *http.Request) {
	req := model.SelectRequest{
		Group:   coalesce(r.URL.Query().Get("group"), "default"),
		Site:    r.URL.Query().Get("site"),
		Policy:  r.URL.Query().Get("policy"),
		TagsAny: splitCSV(r.URL.Query().Get("tags_any")),
	}

	lease, err := h.selector.Next(r.Context(), req)
	if err != nil {
		if err == model.ErrNoProxy {
			writeError(w, http.StatusNotFound, "not_found", "no available proxy")
			return
		}
		if err == model.ErrBadPolicy {
			writeError(w, http.StatusBadRequest, "bad_request", "invalid policy")
			return
		}
		writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
		return
	}

	resp := model.NextProxyResponse{
		Proxy: model.ProxyInfo{
			ID:       lease.Proxy.ID,
			Protocol: lease.Proxy.Protocol,
			Host:     lease.Proxy.Host,
			Port:     lease.Proxy.Port,
		},
		LeaseID: lease.LeaseID,
		TTLMs:   time.Until(lease.ExpireAt).Milliseconds(),
	}

	// 根据配置决定是否返回凭证
	if h.cfg.ReturnSecret {
		resp.Proxy.Username = lease.Proxy.Username
		resp.Proxy.Password = lease.Proxy.Password
	}

	writeJSON(w, http.StatusOK, resp)
}

// HandleReport 上报使用结果
// POST /v1/proxies/report
func (h *Handlers) HandleReport(w http.ResponseWriter, r *http.Request) {
	var req model.ReportRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", "invalid JSON body")
		return
	}

	if req.ProxyID == "" {
		writeError(w, http.StatusBadRequest, "bad_request", "proxy_id is required")
		return
	}

	if err := h.selector.Report(r.Context(), req.LeaseID, req.ProxyID, req.Success, req.LatencyMs, req.Error); err != nil {
		writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
		return
	}

	writeJSON(w, http.StatusOK, map[string]bool{"ok": true})
}

// HandleListProxies 列出代理
// GET /v1/proxies
func (h *Handlers) HandleListProxies(w http.ResponseWriter, r *http.Request) {
	query := r.URL.Query()

	// 解析分页参数
	offset, _ := strconv.Atoi(query.Get("offset"))
	limit, _ := strconv.Atoi(query.Get("limit"))
	if limit <= 0 {
		limit = 20
	}
	if limit > 100 {
		limit = 100
	}

	// 解析过滤参数
	var statusIn []model.ProxyStatus
	if statusStr := query.Get("status"); statusStr != "" {
		for _, s := range strings.Split(statusStr, ",") {
			statusIn = append(statusIn, model.ProxyStatus(strings.TrimSpace(s)))
		}
	}

	q := model.ProxyListQuery{
		Group:       query.Get("group"),
		TagsAny:     splitCSV(query.Get("tags")),
		StatusIn:    statusIn,
		OnlyEnabled: query.Get("only_enabled") == "true",
		Offset:      offset,
		Limit:       limit,
	}

	proxies, total, err := h.store.ListPaginated(r.Context(), q)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
		return
	}

	writeJSON(w, http.StatusOK, model.ProxyListResponse{
		Data:   proxies,
		Total:  total,
		Offset: offset,
		Limit:  limit,
	})
}

// HandleGetProxy 获取单个代理
// GET /v1/proxies/{id}
func (h *Handlers) HandleGetProxy(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	if id == "" {
		writeError(w, http.StatusBadRequest, "bad_request", "proxy id is required")
		return
	}

	proxy, err := h.store.GetByID(r.Context(), id)
	if err != nil {
		if err == model.ErrProxyNotFound {
			writeError(w, http.StatusNotFound, "not_found", "proxy not found")
			return
		}
		writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
		return
	}

	writeJSON(w, http.StatusOK, proxy)
}

// HandleDeleteProxy 删除单个代理
// DELETE /v1/proxies/{id}
func (h *Handlers) HandleDeleteProxy(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	if id == "" {
		writeError(w, http.StatusBadRequest, "bad_request", "proxy id is required")
		return
	}

	if err := h.store.Delete(r.Context(), id); err != nil {
		if err == model.ErrProxyNotFound {
			writeError(w, http.StatusNotFound, "not_found", "proxy not found")
			return
		}
		writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
		return
	}

	writeJSON(w, http.StatusOK, map[string]bool{"ok": true})
}

// HandleBulkDeleteProxies 批量删除代理
// DELETE /v1/proxies
func (h *Handlers) HandleBulkDeleteProxies(w http.ResponseWriter, r *http.Request) {
	var req model.BulkDeleteRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", "invalid JSON body")
		return
	}

	deleted, err := h.store.DeleteMany(r.Context(), req)
	if err != nil {
		if err == model.ErrBulkDeleteEmpty {
			writeError(w, http.StatusBadRequest, "bad_request", err.Error())
			return
		}
		writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
		return
	}

	writeJSON(w, http.StatusOK, model.BulkDeleteResponse{Deleted: int(deleted)})
}

// HandleUpdateProxy 更新代理
// PATCH /v1/proxies/{id}
func (h *Handlers) HandleUpdateProxy(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	if id == "" {
		writeError(w, http.StatusBadRequest, "bad_request", "proxy id is required")
		return
	}

	var patch model.ProxyPatch
	if err := json.NewDecoder(r.Body).Decode(&patch); err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", "invalid JSON body")
		return
	}

	if err := h.store.Update(r.Context(), id, patch); err != nil {
		if err == model.ErrProxyNotFound {
			writeError(w, http.StatusNotFound, "not_found", "proxy not found")
			return
		}
		if err == model.ErrInvalidPatch {
			writeError(w, http.StatusBadRequest, "bad_request", err.Error())
			return
		}
		writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
		return
	}

	// 返回更新后的代理
	proxy, err := h.store.GetByID(r.Context(), id)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
		return
	}

	writeJSON(w, http.StatusOK, proxy)
}

// HandleTestSingleProxy 测试单个代理
// POST /v1/proxies/{id}/test
func (h *Handlers) HandleTestSingleProxy(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	if id == "" {
		writeError(w, http.StatusBadRequest, "bad_request", "proxy id is required")
		return
	}

	var req model.SingleTestRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", "invalid JSON body")
		return
	}

	// SSRF 防护
	if req.URL == "" {
		writeError(w, http.StatusBadRequest, "bad_request", "url is required")
		return
	}
	if err := security.ValidateTestURL(req.URL); err != nil {
		writeError(w, http.StatusBadRequest, "bad_request", err.Error())
		return
	}

	// 获取代理
	proxy, err := h.store.GetByID(r.Context(), id)
	if err != nil {
		if err == model.ErrProxyNotFound {
			writeError(w, http.StatusNotFound, "not_found", "proxy not found")
			return
		}
		writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
		return
	}

	// 构建测试规格
	timeout := time.Duration(req.TimeoutMs) * time.Millisecond
	if timeout <= 0 {
		timeout = 5 * time.Second
	}

	spec := model.TestSpec{
		URL:            req.URL,
		Method:         coalesce(req.Method, "GET"),
		Timeout:        timeout,
		ExpectStatus:   req.ExpectStatus,
		ExpectContains: req.ExpectContains,
	}

	// 执行测试
	results := h.tester.TestBatch(r.Context(), []model.Proxy{*proxy}, spec, 1)
	if len(results) == 0 {
		writeError(w, http.StatusInternalServerError, "internal_error", "test failed")
		return
	}

	result := results[0]

	// 更新数据库
	if req.UpdateStore {
		now := result.CheckedAt
		if result.OK {
			status := model.StatusAlive
			_ = h.store.UpdateHealth(r.Context(), result.ProxyID, model.HealthPatch{
				Status:     &status,
				ScoreDelta: 1,
				SuccessInc: 1,
				LatencyMs:  &result.LatencyMs,
				CheckedAt:  &now,
			})
		} else {
			status := model.StatusDead
			_ = h.store.UpdateHealth(r.Context(), result.ProxyID, model.HealthPatch{
				Status:     &status,
				ScoreDelta: -3,
				FailInc:    1,
				CheckedAt:  &now,
			})
		}
	}

	// 写入测试日志
	if req.WriteLog {
		_ = h.store.InsertTestLog(r.Context(), result, req.URL)
	}

	writeJSON(w, http.StatusOK, result)
}

// HandleGetStats 获取代理统计信息
// GET /v1/proxies/stats
func (h *Handlers) HandleGetStats(w http.ResponseWriter, r *http.Request) {
	stats, err := h.store.GetStats(r.Context())
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal_error", err.Error())
		return
	}

	writeJSON(w, http.StatusOK, stats)
}

// writeJSON 写入 JSON 响应
func writeJSON(w http.ResponseWriter, status int, data any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(data)
}

// writeError 写入错误响应
func writeError(w http.ResponseWriter, status int, code, message string) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(map[string]string{
		"error":   code,
		"message": message,
	})
}

// coalesce 返回第一个非空字符串
func coalesce(values ...string) string {
	for _, v := range values {
		if v != "" {
			return v
		}
	}
	return ""
}

// splitCSV 分割逗号分隔的字符串
func splitCSV(s string) []string {
	if s == "" {
		return nil
	}
	parts := strings.Split(s, ",")
	result := make([]string, 0, len(parts))
	for _, p := range parts {
		p = strings.TrimSpace(p)
		if p != "" {
			result = append(result, p)
		}
	}
	return result
}