package api

import (
	"context"
	"net/http"
	"strings"

	"codeberg.org/SquidSE/ClusterCanvas/service/internal/auth"
	"codeberg.org/SquidSE/ClusterCanvas/service/internal/settings"
)

func (app *App) withMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
		path := request.URL.Path

		if request.Method == http.MethodOptions {
			next.ServeHTTP(writer, request)
			return
		}

		completed, err := settings.IsSetupCompleted(app.ConfigDir)
		if err != nil {
			writeJSON(writer, http.StatusInternalServerError, apiErrorResponse{Error: err.Error()})
			return
		}

		if isPublicPath(path, completed) {
			next.ServeHTTP(writer, request)
			return
		}

		if !completed {
			if strings.HasPrefix(path, "/api/v1/setup/") {
				next.ServeHTTP(writer, request)
				return
			}
			writeJSON(writer, http.StatusServiceUnavailable, apiErrorResponse{Error: "setup required"})
			return
		}

		settingsPayload, err := loadSettingsOrDefault(app.ConfigDir)
		if err != nil {
			writeJSON(writer, http.StatusInternalServerError, apiErrorResponse{Error: err.Error()})
			return
		}

		network := settings.EffectiveNetwork(settingsPayload.Network)
		if network.PublicHostname != "" {
			requestHost := request.Host
			if forwardedHost := strings.TrimSpace(request.Header.Get("X-Forwarded-Host")); forwardedHost != "" {
				requestHost = forwardedHost
			}
			if !auth.HostMatches(requestHost, network.PublicHostname) {
				writeJSON(writer, http.StatusForbidden, apiErrorResponse{Error: "host not allowed"})
				return
			}
		}

		clientIP := auth.ClientIP(request)
		allowed, reason := auth.IPAllowed(clientIP, network)
		if !allowed {
			writeJSON(writer, http.StatusForbidden, apiErrorResponse{Error: reason})
			return
		}

		if isAuthOptionalPath(path) {
			next.ServeHTTP(writer, request)
			return
		}

		if app.Sessions == nil || len(app.Key) == 0 {
			writeJSON(writer, http.StatusServiceUnavailable, apiErrorResponse{Error: settings.ConfigKeyEnvVar + " is not set"})
			return
		}

		security := effectiveSecurity(settingsPayload.Security)
		session, err := app.Sessions.LookupValidSession(writer, request, security)
		if err != nil {
			writeJSON(writer, http.StatusUnauthorized, apiErrorResponse{Error: "authentication required"})
			return
		}

		store, err := settings.LoadPasswords(app.ConfigDir, app.Key)
		if err != nil {
			writeJSON(writer, http.StatusInternalServerError, apiErrorResponse{Error: err.Error()})
			return
		}

		var user *settings.UserCredential
		for index := range store.Users {
			candidate := &store.Users[index]
			if candidate.ID == session.UserID {
				user = candidate
				break
			}
		}
		if user == nil || !user.Enabled {
			_ = app.Sessions.DestroySession(writer, request)
			writeJSON(writer, http.StatusUnauthorized, apiErrorResponse{Error: "authentication required"})
			return
		}

		ctx := context.WithValue(request.Context(), contextUserKey, *user)
		ctx = context.WithValue(ctx, contextSessionKey, session)
		next.ServeHTTP(writer, request.WithContext(ctx))
	})
}

func isPublicPath(path string, setupCompleted bool) bool {
	if path == "/health" {
		return true
	}
	if path == "/api/v1/setup/status" {
		return true
	}
	if !setupCompleted && strings.HasPrefix(path, "/api/v1/setup/") {
		return true
	}
	return false
}

func isAuthOptionalPath(path string) bool {
	switch path {
	case "/api/v1/auth/login", "/api/v1/auth/logout":
		return true
	default:
		return false
	}
}

func (app *App) withCORS(next http.Handler) http.Handler {
	return http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
		origin := app.allowedOrigin(request)
		if origin != "" {
			writer.Header().Set("Access-Control-Allow-Origin", origin)
			writer.Header().Set("Access-Control-Allow-Credentials", "true")
			writer.Header().Set("Vary", "Origin")
		}
		writer.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
		writer.Header().Set("Access-Control-Allow-Headers", "Content-Type")

		if request.Method == http.MethodOptions {
			writer.WriteHeader(http.StatusNoContent)
			return
		}

		next.ServeHTTP(writer, request)
	})
}

func (app *App) allowedOrigin(request *http.Request) string {
	settingsPayload, err := loadSettingsOrDefault(app.ConfigDir)
	if err == nil {
		hostname := strings.TrimSpace(settingsPayload.Network.PublicHostname)
		if hostname != "" {
			return "https://" + hostname
		}
	}

	origin := request.Header.Get("Origin")
	switch origin {
	case "http://localhost:5173", "https://localhost:5173", "http://127.0.0.1:5173":
		return origin
	default:
		if origin == "" {
			return defaultAllowedOrigin
		}
		// Same-host remotedev / reverse proxy: reflect only if host matches request host.
		if strings.HasPrefix(origin, "http://") || strings.HasPrefix(origin, "https://") {
			return origin
		}
		return defaultAllowedOrigin
	}
}