package webui

import (
	"errors"
	"fmt"
	"net/http"
	"os"
	"strings"

	"reanimator/chart/viewer"
	chartweb "reanimator/chart/web"
)

const defaultTitle = "Bee Hardware Audit"

type HandlerOptions struct {
	Title     string
	AuditPath string
}

func NewHandler(opts HandlerOptions) http.Handler {
	title := strings.TrimSpace(opts.Title)
	if title == "" {
		title = defaultTitle
	}

	auditPath := strings.TrimSpace(opts.AuditPath)
	mux := http.NewServeMux()
	mux.Handle("GET /static/", http.StripPrefix("/static/", chartweb.Static()))
	mux.HandleFunc("GET /healthz", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Cache-Control", "no-store")
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte("ok"))
	})
	mux.HandleFunc("GET /audit.json", func(w http.ResponseWriter, r *http.Request) {
		data, err := loadSnapshot(auditPath)
		if err != nil {
			if errors.Is(err, os.ErrNotExist) {
				http.Error(w, "audit snapshot not found", http.StatusNotFound)
				return
			}
			http.Error(w, fmt.Sprintf("read audit snapshot: %v", err), http.StatusInternalServerError)
			return
		}
		w.Header().Set("Cache-Control", "no-store")
		w.Header().Set("Content-Type", "application/json; charset=utf-8")
		_, _ = w.Write(data)
	})
	mux.HandleFunc("GET /", func(w http.ResponseWriter, r *http.Request) {
		snapshot, err := loadSnapshot(auditPath)
		if err != nil && !errors.Is(err, os.ErrNotExist) {
			http.Error(w, fmt.Sprintf("read audit snapshot: %v", err), http.StatusInternalServerError)
			return
		}

		html, err := viewer.RenderHTML(snapshot, title)
		if err != nil {
			http.Error(w, fmt.Sprintf("render snapshot: %v", err), http.StatusInternalServerError)
			return
		}
		w.Header().Set("Cache-Control", "no-store")
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		_, _ = w.Write(html)
	})
	return mux
}

func ListenAndServe(addr string, opts HandlerOptions) error {
	return http.ListenAndServe(addr, NewHandler(opts))
}

func loadSnapshot(path string) ([]byte, error) {
	if strings.TrimSpace(path) == "" {
		return nil, os.ErrNotExist
	}
	return os.ReadFile(path)
}