package httpapi

import (
	"context"
	"fmt"
	"log/slog"
	"net"
	"net/http"
	"runtime/debug"
	"strings"
	"time"

	"calllinesystem/server/internal/config"
	"calllinesystem/server/internal/database"
	"calllinesystem/server/internal/model"
	"calllinesystem/server/internal/security"

	"github.com/google/uuid"
	"gorm.io/gorm"
)

type contextKey string

const (
	principalKey contextKey = "principal"
	requestIDKey contextKey = "request_id"
)

type Server struct {
	db                  *gorm.DB
	config              config.Config
	cipher              *security.Cipher
	logger              *slog.Logger
	hub                 eventPublisher
	loginLimiter        *loginLimiter
	publicQueryLimiter  *queryLimiter
	publicTicketLimiter *queryLimiter
	dummyPassword       string
	now                 func() time.Time
}

func New(db *gorm.DB, cfg config.Config, logger *slog.Logger) (*Server, error) {
	return NewWithEventPublisher(db, cfg, logger, newEventHub())
}

func NewWithEventPublisher(db *gorm.DB, cfg config.Config, logger *slog.Logger, publisher eventPublisher) (*Server, error) {
	fieldCipher, err := security.NewCipher(cfg.EncryptionKey, cfg.PhoneHMACKey)
	if err != nil {
		return nil, err
	}
	if publisher == nil {
		return nil, fmt.Errorf("event publisher is required")
	}
	dummy, err := security.HashPassword("not-a-real-password-value")
	if err != nil {
		return nil, err
	}
	now := func() time.Time { return time.Now().UTC() }
	return &Server{
		db:                  db,
		config:              cfg,
		cipher:              fieldCipher,
		logger:              logger,
		hub:                 publisher,
		loginLimiter:        newLoginLimiter(now),
		publicQueryLimiter:  newQueryLimiter(now, 120, time.Minute),
		publicTicketLimiter: newQueryLimiter(now, 20, time.Minute),
		dummyPassword:       dummy,
		now:                 now,
	}, nil
}

func (s *Server) Handler() http.Handler {
	mux := http.NewServeMux()
	mux.HandleFunc("GET /healthz", s.health)
	mux.HandleFunc("GET /readyz", s.ready)
	mux.HandleFunc("POST /api/staff/auth/login", s.loginFor(model.RoleStaff))
	mux.Handle("POST /api/staff/auth/logout", s.requireStaff(s.logoutFor(model.RoleStaff)))
	mux.Handle("GET /api/staff/auth/me", s.requireStaff(http.HandlerFunc(s.me)))
	mux.HandleFunc("POST /api/admin/auth/login", s.loginFor(model.RoleAdmin))
	mux.Handle("POST /api/admin/auth/logout", s.requireAdmin(s.logoutFor(model.RoleAdmin)))
	mux.Handle("GET /api/admin/auth/me", s.requireAdmin(http.HandlerFunc(s.me)))
	mux.Handle("GET /api/staff/projects", s.requireStaff(http.HandlerFunc(s.staffProjects)))
	mux.Handle("GET /api/staff/projects/{id}/queue", s.requireStaff(http.HandlerFunc(s.queueSnapshot)))
	mux.Handle("POST /api/staff/projects/{id}/tickets", s.requireStaff(http.HandlerFunc(s.createTicket)))
	mux.Handle("POST /api/staff/projects/{id}/call-next", s.requireStaff(http.HandlerFunc(s.callNext)))
	mux.HandleFunc("GET /api/public/status/{token}", s.publicStatus)
	mux.HandleFunc("GET /api/public/projects", s.publicProjects)
	mux.HandleFunc("POST /api/public/projects/{id}/tickets", s.publicCreateTicket)
	mux.HandleFunc("POST /api/public/status/search", s.publicStatusByPhone)
	mux.Handle("POST /api/internal/status/search", s.requireInternalNetwork(http.HandlerFunc(s.internalStatusByPhone)))
	mux.HandleFunc("GET /api/display/{token}/snapshot", s.displaySnapshot)
	mux.Handle("GET /api/events", s.requireStaff(http.HandlerFunc(s.events)))
	mux.Handle("GET /api/admin/overview", s.requireAdmin(http.HandlerFunc(s.adminOverview)))
	mux.Handle("GET /api/admin/users", s.requireAdmin(http.HandlerFunc(s.adminUsers)))
	mux.Handle("POST /api/admin/users", s.requireAdmin(http.HandlerFunc(s.createAdminUser)))
	mux.Handle("PUT /api/admin/users/{id}", s.requireAdmin(http.HandlerFunc(s.updateAdminUser)))
	mux.Handle("POST /api/admin/projects", s.requireAdmin(http.HandlerFunc(s.createProject)))
	mux.Handle("PUT /api/admin/projects/{id}", s.requireAdmin(http.HandlerFunc(s.updateProject)))
	mux.Handle("PUT /api/admin/projects/{id}/settings", s.requireAdmin(http.HandlerFunc(s.updateProjectSettings)))
	mux.Handle("GET /api/admin/history/tickets", s.requireAdmin(http.HandlerFunc(s.adminHistoryTickets)))
	mux.Handle("GET /api/admin/history/tickets/{id}", s.requireAdmin(http.HandlerFunc(s.adminHistoryTicket)))
	mux.Handle("GET /api/admin/history/batches", s.requireAdmin(http.HandlerFunc(s.adminHistoryBatches)))
	mux.Handle("GET /api/admin/history/batches/{id}", s.requireAdmin(http.HandlerFunc(s.adminHistoryBatch)))
	mux.Handle("GET /api/admin/history/summary", s.requireAdmin(http.HandlerFunc(s.adminHistorySummary)))
	mux.Handle("GET /api/admin/history/export.csv", s.requireAdmin(http.HandlerFunc(s.adminHistoryExport)))
	return s.requestID(s.accessLog(s.recoverPanic(s.securityHeaders(mux))))
}

func (s *Server) health(w http.ResponseWriter, _ *http.Request) {
	writeJSON(w, http.StatusOK, map[string]any{"status": "ok", "time": s.now()})
}

func (s *Server) ready(w http.ResponseWriter, r *http.Request) {
	sqlDB, err := s.db.DB()
	if err != nil {
		writeError(w, err)
		return
	}
	ctx, cancel := context.WithTimeout(r.Context(), 2*time.Second)
	defer cancel()
	if err := sqlDB.PingContext(ctx); err != nil {
		writeJSON(w, http.StatusServiceUnavailable, map[string]any{"status": "not_ready"})
		return
	}
	if err := database.SchemaReady(ctx, sqlDB); err != nil {
		s.logger.Warn("database schema is not ready", "error", err)
		writeJSON(w, http.StatusServiceUnavailable, map[string]any{"status": "not_ready"})
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"status": "ready"})
}

func (s *Server) requestID(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		requestID := strings.TrimSpace(r.Header.Get("X-Request-ID"))
		if len(requestID) < 8 || len(requestID) > 80 {
			requestID = uuid.NewString()
		}
		w.Header().Set("X-Request-ID", requestID)
		next.ServeHTTP(w, r.WithContext(context.WithValue(r.Context(), requestIDKey, requestID)))
	})
}

type statusRecorder struct {
	http.ResponseWriter
	status      int
	wroteHeader bool
	body        *logBodyCapture
}

func (r *statusRecorder) WriteHeader(status int) {
	if r.wroteHeader {
		return
	}
	r.status = status
	r.wroteHeader = true
	r.ResponseWriter.WriteHeader(status)
}

func (r *statusRecorder) Write(value []byte) (int, error) {
	if !r.wroteHeader {
		r.WriteHeader(http.StatusOK)
	}
	n, err := r.ResponseWriter.Write(value)
	if n > 0 && r.body != nil {
		_, _ = r.body.Write(value[:n])
	}
	return n, err
}

func (r *statusRecorder) Unwrap() http.ResponseWriter {
	return r.ResponseWriter
}

func (r *statusRecorder) responseStarted() bool {
	return r.wroteHeader
}

type flushStatusRecorder struct {
	*statusRecorder
}

func (r *flushStatusRecorder) Flush() {
	if !r.wroteHeader {
		r.WriteHeader(http.StatusOK)
	}
	r.ResponseWriter.(http.Flusher).Flush()
}

func (s *Server) accessLog(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		started := s.now()
		var requestBody *logBodyCapture
		var responseBody *logBodyCapture
		if shouldCaptureLogBody(r) {
			requestBody = &logBodyCapture{}
			responseBody = &logBodyCapture{}
			if r.Body != nil {
				r.Body = &logCaptureReadCloser{ReadCloser: r.Body, capture: requestBody}
			}
		}
		recorder := &statusRecorder{ResponseWriter: w, status: http.StatusOK, body: responseBody}
		var responseWriter http.ResponseWriter = recorder
		if _, ok := w.(http.Flusher); ok {
			responseWriter = &flushStatusRecorder{statusRecorder: recorder}
		}
		next.ServeHTTP(responseWriter, r)
		attributes := []any{
			"request_id", requestID(r.Context()),
			"method", r.Method,
			"path", logPath(r),
			"status", recorder.status,
			"duration_ms", time.Since(started).Milliseconds(),
		}
		if isImportantLogRoute(r) {
			if request := requestLogDetails(r, requestBody); request != nil {
				attributes = append(attributes, "request", request)
			}
			if response := responseLogDetails(r, recorder); response != nil {
				attributes = append(attributes, "response", response)
			}
		}
		s.logger.Info("http request", attributes...)
	})
}

func (s *Server) securityHeaders(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("X-Content-Type-Options", "nosniff")
		w.Header().Set("X-Frame-Options", "DENY")
		w.Header().Set("Referrer-Policy", "no-referrer")
		w.Header().Set("Cache-Control", "no-store")
		next.ServeHTTP(w, r)
	})
}

func (s *Server) recoverPanic(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer func() {
			if recovered := recover(); recovered != nil {
				responseStarted := false
				if state, ok := w.(interface{ responseStarted() bool }); ok {
					responseStarted = state.responseStarted()
				}
				s.logger.Error("panic recovered",
					"request_id", requestID(r.Context()),
					"error", recovered,
					"response_started", responseStarted,
					"stack", string(debug.Stack()),
				)
				if responseStarted {
					return
				}
				writeError(w, fmt.Errorf("panic: %v", recovered))
			}
		}()
		next.ServeHTTP(w, r)
	})
}

func requestID(ctx context.Context) string {
	value, _ := ctx.Value(requestIDKey).(string)
	return value
}

func remoteIP(r *http.Request) *string {
	host, _, err := net.SplitHostPort(r.RemoteAddr)
	if err != nil {
		host = r.RemoteAddr
	}
	if net.ParseIP(host) == nil {
		return nil
	}
	return &host
}

func boundedUserAgent(r *http.Request) string {
	value := r.UserAgent()
	if len(value) > 512 {
		return value[:512]
	}
	return value
}