package webui

import (
	"errors"
	"fmt"
	"html"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"sort"
	"strings"

	"bee/audit/internal/app"
	"reanimator/chart/viewer"
	chartweb "reanimator/chart/web"
)

const defaultTitle = "Bee Hardware Audit"

type HandlerOptions struct {
	Title     string
	AuditPath string
	ExportDir string
}

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

	auditPath := strings.TrimSpace(opts.AuditPath)
	exportDir := strings.TrimSpace(opts.ExportDir)
	if exportDir == "" {
		exportDir = app.DefaultExportDir
	}
	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 /export/support.tar.gz", func(w http.ResponseWriter, r *http.Request) {
		archive, err := app.BuildSupportBundle(exportDir)
		if err != nil {
			http.Error(w, fmt.Sprintf("build support bundle: %v", err), http.StatusInternalServerError)
			return
		}
		w.Header().Set("Cache-Control", "no-store")
		w.Header().Set("Content-Type", "application/gzip")
		w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%q", filepath.Base(archive)))
		http.ServeFile(w, r, archive)
	})
	mux.HandleFunc("GET /runtime-health.json", func(w http.ResponseWriter, r *http.Request) {
		data, err := loadSnapshot(filepath.Join(exportDir, "runtime-health.json"))
		if err != nil {
			if errors.Is(err, os.ErrNotExist) {
				http.Error(w, "runtime health not found", http.StatusNotFound)
				return
			}
			http.Error(w, fmt.Sprintf("read runtime health: %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 /export/", func(w http.ResponseWriter, r *http.Request) {
		body, err := renderExportIndex(exportDir)
		if err != nil {
			http.Error(w, fmt.Sprintf("render export index: %v", err), http.StatusInternalServerError)
			return
		}
		w.Header().Set("Cache-Control", "no-store")
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		_, _ = w.Write([]byte(body))
	})
	mux.HandleFunc("GET /export/file", func(w http.ResponseWriter, r *http.Request) {
		rel := strings.TrimSpace(r.URL.Query().Get("path"))
		if rel == "" {
			http.Error(w, "path is required", http.StatusBadRequest)
			return
		}
		clean := filepath.Clean(rel)
		if clean == "." || strings.HasPrefix(clean, "..") {
			http.Error(w, "invalid path", http.StatusBadRequest)
			return
		}
		http.ServeFile(w, r, filepath.Join(exportDir, clean))
	})
	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
		}
		noticeTitle, noticeBody := runtimeNotice(filepath.Join(exportDir, "runtime-health.json"))
		html, err := viewer.RenderHTMLWithOptions(snapshot, title, viewer.RenderOptions{
			DownloadArchiveURL:   "/export/support.tar.gz",
			DownloadArchiveLabel: "Download support bundle",
			NoticeTitle:          noticeTitle,
			NoticeBody:           noticeBody,
		})
		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)
}

func runtimeNotice(path string) (string, string) {
	health, err := app.ReadRuntimeHealth(path)
	if err != nil {
		return "Runtime Health", "No runtime health snapshot found yet."
	}
	body := fmt.Sprintf("Status: %s. Export dir: %s. Driver ready: %t. CUDA ready: %t. Network: %s. Export files: /export/",
		firstNonEmpty(health.Status, "UNKNOWN"),
		firstNonEmpty(health.ExportDir, app.DefaultExportDir),
		health.DriverReady,
		health.CUDAReady,
		firstNonEmpty(health.NetworkStatus, "UNKNOWN"),
	)
	if len(health.Issues) > 0 {
		body += " Issues: "
		parts := make([]string, 0, len(health.Issues))
		for _, issue := range health.Issues {
			parts = append(parts, issue.Code)
		}
		body += strings.Join(parts, ", ")
	}
	return "Runtime Health", body
}

func renderExportIndex(exportDir string) (string, error) {
	var entries []string
	err := filepath.Walk(strings.TrimSpace(exportDir), func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.IsDir() {
			return nil
		}
		rel, err := filepath.Rel(exportDir, path)
		if err != nil {
			return err
		}
		entries = append(entries, rel)
		return nil
	})
	if err != nil && !errors.Is(err, os.ErrNotExist) {
		return "", err
	}
	sort.Strings(entries)
	var body strings.Builder
	body.WriteString("<!DOCTYPE html><html><head><meta charset=\"utf-8\"><title>Bee Export Files</title></head><body>")
	body.WriteString("<h1>Bee Export Files</h1><ul>")
	for _, entry := range entries {
		body.WriteString("<li><a href=\"/export/file?path=" + url.QueryEscape(entry) + "\">" + html.EscapeString(entry) + "</a></li>")
	}
	if len(entries) == 0 {
		body.WriteString("<li>No export files found.</li>")
	}
	body.WriteString("</ul></body></html>")
	return body.String(), nil
}

func firstNonEmpty(value, fallback string) string {
	value = strings.TrimSpace(value)
	if value == "" {
		return fallback
	}
	return value
}