// Package http provides the HTTP server and routing functionality.
package http

import (
	"encoding/json"
	"log/slog"
	"net"
	"net/http"
	"strings"

	"git.eeqj.de/sneak/ipapi/internal/database"
	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
)

// IPInfo represents the API response for IP lookups.
type IPInfo struct {
	IP          string  `json:"ip"`
	Country     string  `json:"country,omitempty"`
	CountryCode string  `json:"countryCode,omitempty"`
	City        string  `json:"city,omitempty"`
	Region      string  `json:"region,omitempty"`
	PostalCode  string  `json:"postalCode,omitempty"`
	Latitude    float64 `json:"latitude,omitempty"`
	Longitude   float64 `json:"longitude,omitempty"`
	Timezone    string  `json:"timezone,omitempty"`
	ASN         uint    `json:"asn,omitempty"`
	ASNOrg      string  `json:"asnOrg,omitempty"`
}

// NewRouter creates a new HTTP router with all endpoints configured.
func NewRouter(logger *slog.Logger, db *database.Manager) (chi.Router, error) {
	r := chi.NewRouter()

	// Middleware
	r.Use(middleware.RequestID)
	r.Use(middleware.RealIP)
	r.Use(middleware.Recoverer)
	const requestTimeout = 60
	r.Use(middleware.Timeout(requestTimeout))

	// Logging middleware
	r.Use(func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			start := r.Context().Value(middleware.RequestIDKey).(string)
			logger.Debug("HTTP request",
				"method", r.Method,
				"path", r.URL.Path,
				"remote_addr", r.RemoteAddr,
				"request_id", start,
			)
			next.ServeHTTP(w, r)
		})
	})

	// Health check
	r.Get("/health", func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusOK)
		if _, err := w.Write([]byte("OK")); err != nil {
			logger.Error("Failed to write health response", "error", err)
		}
	})

	// IP lookup endpoint
	r.Get("/api/{ip}", handleIPLookup(logger, db))

	return r, nil
}

func handleIPLookup(logger *slog.Logger, db *database.Manager) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		ipStr := chi.URLParam(r, "ip")

		// Validate IP address
		ip := net.ParseIP(ipStr)
		if ip == nil {
			writeError(w, http.StatusBadRequest, "Invalid IP address")

			return
		}

		info := &IPInfo{
			IP: ipStr,
		}

		// Look up in Country database
		if countryDB := db.GetCountryDB(); countryDB != nil {
			country, err := countryDB.Country(ip)
			if err == nil {
				info.Country = country.Country.Names["en"]
				info.CountryCode = country.Country.IsoCode
			}
		}

		// Look up in City database
		if cityDB := db.GetCityDB(); cityDB != nil {
			city, err := cityDB.City(ip)
			if err == nil {
				info.City = city.City.Names["en"]
				if len(city.Subdivisions) > 0 {
					info.Region = city.Subdivisions[0].Names["en"]
				}
				info.PostalCode = city.Postal.Code
				info.Latitude = city.Location.Latitude
				info.Longitude = city.Location.Longitude
				info.Timezone = city.Location.TimeZone
			}
		}

		// Look up in ASN database
		if asnDB := db.GetASNDB(); asnDB != nil {
			asn, err := asnDB.ASN(ip)
			if err == nil {
				info.ASN = asn.AutonomousSystemNumber
				info.ASNOrg = asn.AutonomousSystemOrganization
			}
		}

		// Set content type and encode response
		w.Header().Set("Content-Type", "application/json")
		if err := json.NewEncoder(w).Encode(info); err != nil {
			logger.Error("Failed to encode response", "error", err)
			writeError(w, http.StatusInternalServerError, "Internal server error")
		}
	}
}

func writeError(w http.ResponseWriter, code int, message string) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(code)
	if err := json.NewEncoder(w).Encode(map[string]string{
		"error": message,
	}); err != nil {
		// Log error but don't try to write again
		_ = err
	}
}

//nolint:unused // will be used in future for rate limiting
func getClientIP(r *http.Request) string {
	// Check X-Forwarded-For header
	if xff := r.Header.Get("X-Forwarded-For"); xff != "" {
		ips := strings.Split(xff, ",")
		if len(ips) > 0 {
			return strings.TrimSpace(ips[0])
		}
	}

	// Check X-Real-IP header
	if xri := r.Header.Get("X-Real-IP"); xri != "" {
		return xri
	}

	// Fall back to RemoteAddr
	host, _, _ := net.SplitHostPort(r.RemoteAddr)

	return host
}