// Package api provides HTTP handlers and middleware for the Silo API.
package api

import (
	"crypto/sha256"
	"encoding/hex"
	"net/http"
	"strings"
	"time"

	"github.com/go-chi/chi/v5/middleware"
	"github.com/kindredsystems/silo/internal/auth"
	"github.com/rs/zerolog"
)

// RequestLogger returns a middleware that logs HTTP requests using zerolog.
func RequestLogger(logger zerolog.Logger) func(next http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			start := time.Now()
			ww := middleware.NewWrapResponseWriter(w, r.ProtoMajor)

			defer func() {
				logger.Info().
					Str("method", r.Method).
					Str("path", r.URL.Path).
					Str("query", r.URL.RawQuery).
					Int("status", ww.Status()).
					Int("bytes", ww.BytesWritten()).
					Dur("duration", time.Since(start)).
					Str("remote", r.RemoteAddr).
					Str("user_agent", r.UserAgent()).
					Msg("request")
			}()

			next.ServeHTTP(ww, r)
		})
	}
}

// Recoverer returns a middleware that recovers from panics and logs them.
func Recoverer(logger zerolog.Logger) func(next http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			defer func() {
				if rec := recover(); rec != nil {
					logger.Error().
						Interface("panic", rec).
						Str("method", r.Method).
						Str("path", r.URL.Path).
						Msg("panic recovered")

					http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
				}
			}()

			next.ServeHTTP(w, r)
		})
	}
}

// RequireAuth extracts the user from a session cookie or API token and injects
// it into the request context. If auth is disabled, injects a synthetic dev user.
func (s *Server) RequireAuth(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Dev mode: inject synthetic admin user
		if s.authConfig == nil || !s.authConfig.Enabled {
			devUser := &auth.User{
				ID:          "00000000-0000-0000-0000-000000000000",
				Username:    "dev",
				DisplayName: "Developer",
				Email:       "dev@localhost",
				Role:        auth.RoleAdmin,
				AuthSource:  "local",
			}
			ctx := auth.ContextWithUser(r.Context(), devUser)
			next.ServeHTTP(w, r.WithContext(ctx))
			return
		}

		// 1. Check for API token (Authorization: Bearer silo_...)
		if token := extractBearerToken(r); token != "" {
			user, err := s.auth.ValidateToken(r.Context(), token)
			if err != nil {
				writeError(w, http.StatusUnauthorized, "invalid_token", "Invalid or expired API token")
				return
			}
			ctx := auth.ContextWithUser(r.Context(), user)
			next.ServeHTTP(w, r.WithContext(ctx))
			return
		}

		// 2. Check session
		if s.sessions != nil {
			userID := s.sessions.GetString(r.Context(), "user_id")
			if userID != "" {
				user, err := s.auth.GetUserByID(r.Context(), userID)
				if err == nil && user != nil {
					ctx := auth.ContextWithUser(r.Context(), user)
					next.ServeHTTP(w, r.WithContext(ctx))
					return
				}
				// Invalid session — destroy it
				_ = s.sessions.Destroy(r.Context())
			}
		}

		// 3. Not authenticated
		if isAPIRequest(r) {
			writeError(w, http.StatusUnauthorized, "unauthorized", "Authentication required")
		} else {
			next := r.URL.Path
			if r.URL.RawQuery != "" {
				next += "?" + r.URL.RawQuery
			}
			http.Redirect(w, r, "/login?next="+next, http.StatusSeeOther)
		}
	})
}

// RequireRole returns middleware that rejects users below the given role.
// Role hierarchy: admin > editor > viewer.
func (s *Server) RequireRole(minimum string) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			user := auth.UserFromContext(r.Context())
			if user == nil {
				writeError(w, http.StatusUnauthorized, "unauthorized", "Authentication required")
				return
			}
			if !auth.RoleSatisfies(user.Role, minimum) {
				writeError(w, http.StatusForbidden, "forbidden",
					"Insufficient permissions: requires "+minimum+" role")
				return
			}
			next.ServeHTTP(w, r)
		})
	}
}

// RequireWritable rejects requests with 503 when the server is in read-only mode.
func (s *Server) RequireWritable(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if s.serverState.IsReadOnly() {
			writeError(w, http.StatusServiceUnavailable, "server_read_only",
				"Server is in read-only mode")
			return
		}
		next.ServeHTTP(w, r)
	})
}

// RequireRunnerAuth extracts and validates a runner token from the
// Authorization header. On success, injects RunnerIdentity into context
// and updates the runner's heartbeat.
func (s *Server) RequireRunnerAuth(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		token := extractBearerToken(r)
		if token == "" || !strings.HasPrefix(token, "silo_runner_") {
			writeError(w, http.StatusUnauthorized, "unauthorized", "Runner token required")
			return
		}

		hash := sha256.Sum256([]byte(token))
		tokenHash := hex.EncodeToString(hash[:])

		runner, err := s.jobs.GetRunnerByToken(r.Context(), tokenHash)
		if err != nil || runner == nil {
			writeError(w, http.StatusUnauthorized, "unauthorized", "Invalid runner token")
			return
		}

		// Update heartbeat on every authenticated request
		_ = s.jobs.Heartbeat(r.Context(), runner.ID)

		identity := &auth.RunnerIdentity{
			ID:   runner.ID,
			Name: runner.Name,
			Tags: runner.Tags,
		}
		ctx := auth.ContextWithRunner(r.Context(), identity)
		next.ServeHTTP(w, r.WithContext(ctx))
	})
}

// RequireModule returns middleware that rejects requests with 404 when
// the named module is not enabled.
func (s *Server) RequireModule(id string) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			if !s.modules.IsEnabled(id) {
				w.Header().Set("Content-Type", "application/json")
				w.WriteHeader(http.StatusNotFound)
				w.Write([]byte(`{"error":"module '` + id + `' is not enabled"}`))
				return
			}
			next.ServeHTTP(w, r)
		})
	}
}

func extractBearerToken(r *http.Request) string {
	h := r.Header.Get("Authorization")
	if strings.HasPrefix(h, "Bearer ") {
		return strings.TrimPrefix(h, "Bearer ")
	}
	return ""
}

func isAPIRequest(r *http.Request) bool {
	return strings.HasPrefix(r.URL.Path, "/api/")
}