package main

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"strings"
)

type WellKnownGetter interface {
	GetData(ctx context.Context) (wkRegistry, error)
}

// GetHealthServer returns a simple health check handler.
func GetHealthServer() http.Handler {
	mux := http.NewServeMux()

	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
		endpoint := "/healthz"
		requestCounter.WithLabelValues(endpoint).Inc()

		w.WriteHeader(http.StatusOK)
		w.Write([]byte("OK"))
	})

	return mux
}

// GetServer returns an HTTP handler that serves the well-known endpoints.
func GetServer(wks WellKnownGetter) http.Handler {
	mux := http.NewServeMux()

	mux.HandleFunc("/.well-known/", func(w http.ResponseWriter, r *http.Request) {
		ctx := r.Context()
		reg, err := wks.GetData(ctx)
		if err != nil {
			http.Error(w, "Failed to fetch well-known records", http.StatusInternalServerError)
			return
		}

		// Extract the ID from the URL path (strip the prefix)
		id := strings.TrimPrefix(r.URL.Path, "/.well-known/")
		if id == "" {
			errorCounter.WithLabelValues(id).Inc()
			http.Error(w, "Not found", http.StatusNotFound)
			return
		}

		// First, try the exact match
		val, ok := reg[id]

		// If a match is found, check for the format annotation
		if ok {
			data := val.(map[string]interface{})["data"]
			format := val.(map[string]interface{})["format"]

			// If the format is locked to JSON, always return application/json
			if format == "json" {
				w.Header().Set("Content-Type", "application/json")
				b, err := json.Marshal(data)
				if err != nil {
					http.Error(w, "Failed to encode JSON", http.StatusInternalServerError)
					errorCounter.WithLabelValues(id).Inc()
					return
				}
				w.Write(b)
				requestCounter.WithLabelValues(id).Inc()
				return
			} else if format == "text" {
				w.Header().Set("Content-Type", "text/plain; charset=utf-8")
				switch v := data.(type) {
				case []string:
					fmt.Fprint(w, strings.Join(v, "\n"))
					requestCounter.WithLabelValues(id).Inc()
				case string:
					fmt.Fprint(w, v)
					requestCounter.WithLabelValues(id).Inc()
				default:
					http.Error(w, "Unsupported data type for text/plain format", http.StatusInternalServerError)
					errorCounter.WithLabelValues(id).Inc()
				}
				return
			}
		}

		// If no match is found, return 404
		errorCounter.WithLabelValues(id).Inc()
		http.Error(w, "Not found", http.StatusNotFound)
	})

	return mux
}