package server

import (
	"bytes"
	_ "embed"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/david/knox/internal/db"
)

type Server struct {
	kdb  *db.KnoxDB
	mux  *http.ServeMux
	tmpl *template.Template
}

func New(kdb *db.KnoxDB) *Server {
	s := &Server{kdb: kdb, mux: http.NewServeMux()}
	s.tmpl = template.Must(template.New("knox").Funcs(template.FuncMap{
		"shortFP":     shortFP,
		"trunc":       truncStr,
		"fpURL":       fpURL,
		"humanTime":   humanTime,
		"displayTime": displayTime,
	}).Parse(layout))

	s.mux.HandleFunc("GET /", s.dashboard)
	s.mux.HandleFunc("GET /search", s.search)
	s.mux.HandleFunc("GET /threads", s.threadList)
	s.mux.HandleFunc("GET /threads/{id}", s.threadDetail)
	s.mux.HandleFunc("GET /entries/{fp}", s.entryDetail)
	s.mux.HandleFunc("GET /stats", s.stats)
	return s
}

func (s *Server) Serve(addr string) error {
	log.Printf("[knox] web UI at http://%s", addr)
	srv := &http.Server{Addr: addr, Handler: s.mux, ReadHeaderTimeout: 10 * time.Second, IdleTimeout: 60 * time.Second}
	return srv.ListenAndServe()
}

// ─── Dashboard ───────────────────────────────────────────────

func (s *Server) dashboard(w http.ResponseWriter, r *http.Request) {
	gitea, _ := s.kdb.RecentEntriesBySource("gitea", 3)
	obsidian, _ := s.kdb.RecentEntriesBySource("obsidian", 3)
	skills, _ := s.kdb.RecentEntriesBySource("skills-catalog", 2)
	session, _ := s.kdb.RecentEntriesBySource("opencode-session", 3)
	recent, _ := s.kdb.RecentEntries(8)

	goldenID, err := s.kdb.GoldenThreadID()
	if err != nil {
		http.Error(w, "failed to load golden thread", http.StatusInternalServerError)
		return
	}
	var golden *db.Thread
	if goldenID > 0 {
		golden, _ = s.kdb.GetThread(goldenID)
	}
	s.render(w, "dashboard", map[string]any{
		"gitea":    gitea,
		"obsidian": obsidian,
		"skills":   skills,
		"session":  session,
		"recent":   recent,
		"golden":   golden,
	})
}

// ─── Search ──────────────────────────────────────────────────

func (s *Server) search(w http.ResponseWriter, r *http.Request) {
	q := r.URL.Query().Get("q")
	if q == "" {
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		w.Write([]byte("<p class='text-gray-400 text-sm'>Enter a query above.</p>"))
		return
	}
	results, err := s.kdb.Search(q, 30)
	if err != nil {
		http.Error(w, "search failed", http.StatusInternalServerError)
		return
	}
	s.render(w, "search_results", map[string]any{
		"query":   q,
		"results": results,
	})
}

// ─── Thread List ─────────────────────────────────────────────

func (s *Server) threadList(w http.ResponseWriter, r *http.Request) {
	status := r.URL.Query().Get("status")
	threads, err := s.kdb.ListThreads(status)
	if err != nil {
		http.Error(w, "failed to load threads", http.StatusInternalServerError)
		return
	}
	s.render(w, "thread_list", map[string]any{
		"title":   "Threads",
		"threads": threads,
		"status":  status,
	})
}

// ─── Thread Detail ───────────────────────────────────────────

func (s *Server) threadDetail(w http.ResponseWriter, r *http.Request) {
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		http.Error(w, "invalid thread id", http.StatusBadRequest)
		return
	}
	t, err := s.kdb.GetThread(id)
	if err != nil {
		http.Error(w, "failed to load thread", http.StatusInternalServerError)
		return
	}
	if t == nil {
		s.render(w, "not_found", map[string]any{"title": "Thread Not Found"}, http.StatusNotFound)
		return
	}
	obs, err := s.kdb.ThreadObservations(id)
	if err != nil {
		http.Error(w, "failed to load observations", http.StatusInternalServerError)
		return
	}
	notes, err := s.kdb.ThreadNotes(id)
	if err != nil {
		http.Error(w, "failed to load notes", http.StatusInternalServerError)
		return
	}
	provenance, err := s.kdb.ThreadProvenance(id)
	if err != nil {
		http.Error(w, "failed to load provenance", http.StatusInternalServerError)
		return
	}
	goldenID, _ := s.kdb.GoldenThreadID()

	s.render(w, "thread_detail", map[string]any{
		"title":      fmt.Sprintf("Thread #%d", id),
		"thread":     t,
		"obs":        obs,
		"notes":      notes,
		"provenance": provenance,
		"isGolden":   goldenID == id,
	})
}

// ─── Entry Detail ────────────────────────────────────────────

func (s *Server) entryDetail(w http.ResponseWriter, r *http.Request) {
	fp := r.PathValue("fp")
	entry, err := s.kdb.FindEntry(fp)
	if err != nil {
		http.Error(w, "failed to load entry", http.StatusInternalServerError)
		return
	}
	if entry == nil {
		// Try fingerprint prefix match (the UI displays 8-char prefixes)
		entries, err := s.kdb.FindEntryByPrefix(fp, 2)
		if err != nil {
			http.Error(w, "failed to load entry", http.StatusInternalServerError)
			return
		}
		if len(entries) == 1 {
			entry = &entries[0]
		} else {
			s.render(w, "not_found", map[string]any{"title": "Entry Not Found"}, http.StatusNotFound)
			return
		}
	}
	obs, err := s.kdb.ObservationsByFingerprint(entry.Fingerprint, 20)
	if err != nil {
		http.Error(w, "failed to load observations", http.StatusInternalServerError)
		return
	}
	s.render(w, "entry_detail", map[string]any{
		"title": "Entry " + shortFP(entry.Fingerprint),
		"entry": entry,
		"obs":   obs,
	})
}

// ─── Stats Fragment ──────────────────────────────────────────

type statItem struct {
	Label string
	Value any
}

func statItems(stats map[string]any) []statItem {
	keys := make([]string, 0, len(stats))
	for k := range stats {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	items := make([]statItem, 0, len(keys))
	for _, k := range keys {
		items = append(items, statItem{
			Label: strings.ReplaceAll(k, "_", " "),
			Value: stats[k],
		})
	}
	return items
}

func (s *Server) stats(w http.ResponseWriter, r *http.Request) {
	stats, err := s.kdb.Stats()
	if err != nil {
		http.Error(w, "failed to load stats", http.StatusInternalServerError)
		return
	}
	s.render(w, "stats", map[string]any{"stats": statItems(stats)})
}

// ─── Render ──────────────────────────────────────────────────

func (s *Server) render(w http.ResponseWriter, name string, data map[string]any, status ...int) {
	code := http.StatusOK
	if len(status) > 0 {
		code = status[0]
	}
	var buf bytes.Buffer
	if err := s.tmpl.ExecuteTemplate(&buf, name, data); err != nil {
		log.Printf("[knox] template error: %v", err)
		http.Error(w, "template error", http.StatusInternalServerError)
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	w.WriteHeader(code)
	buf.WriteTo(w)
}

func shortFP(fp string) string {
	if len(fp) > 8 {
		return fp[:8]
	}
	return fp
}

// fpURL routes synthetic thread fingerprints to thread pages.
func fpURL(fp string) string {
	if id, ok := strings.CutPrefix(fp, "thread:"); ok {
		return "/threads/" + id
	}
	return "/entries/" + fp
}

func truncStr(s string, n int) string {
	runes := []rune(s)
	if len(runes) <= n {
		return s
	}
	return string(runes[:n]) + "..."
}

func displayTime(e db.Entry) string {
	if e.CreatedAt != "" {
		return humanTime(e.CreatedAt)
	}
	return humanTime(e.LastSeen)
}

func humanTime(s string) string {
	formats := []string{time.RFC3339, "2006-01-02 15:04:05"}
	for _, f := range formats {
		t, err := time.Parse(f, s)
		if err == nil {
			return t.Local().Format("Jan 2, 2006 · 15:04")
		}
	}
	return s
}

//go:embed layout.html
var layout string