package main

import (
	"cmp"
	"context"
	"embed"
	"encoding/binary"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"html/template"
	"io"
	"io/fs"
	"log"
	"net"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"strings"
	"time"

	"github.com/coder/websocket"
	"github.com/kami/maven/internal/audio"
	"github.com/kami/maven/internal/ipc"
	"github.com/kami/maven/internal/voice"
)

// presenceSignals — the only fact keys /api/signal may write. mavweb is a
// network-facing surface inside wg; an allowlist keeps a compromised caller
// boxed to forging weak presence signals (reachability, multi-source, never
// truth) — it can't write arbitrary facts. ponytail: floor auth (wg-only); a
// per-signal token belongs here if the tunnel ever hosts untrusted devices.
var presenceSignals = map[string]string{
	"desk_active":    "infer:hyprland",
	"page_heartbeat": "infer:heartbeat",
	"wg_handshake":   "infer:wg",
}

//go:embed static/*
var staticFiles embed.FS

//go:embed dash.html
var dashHTML string

// dashTmpl — the monitoring read surface, server-rendered from dash.html (no JS,
// no client fetch); meta-refresh keeps it live. html/template escapes the user
// text in facts/nudges. Read-only: browses the append-only store via CoreAPI,
// never writes — the store IS the audit trail, this just shows it.
var dashTmpl = template.Must(template.New("dash").Funcs(template.FuncMap{
	"ago": func(t time.Time) string { return time.Since(t).Round(time.Second).String() + " ago" },
}).Parse(dashHTML))

func noCache(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
		h.ServeHTTP(w, r)
	})
}

func main() {
	addr := flag.String("addr", ":9200", "HTTP listen address")
	voiceAddr := flag.String("voice", "127.0.0.1:9100", "voice server TCP addr (host:port)")
	// ntfyWS: the ntfy WebSocket subscribe URL the PWA connects to for in-app
	// nudge delivery, e.g. wss://ntfy.kvmx.ru/maven/ws?auth=<base64-token>. The
	// client subscribes directly (lowest overhead — mavweb isn't in the path);
	// we only serve it the URL so the deny-all auth token stays deployment
	// config, never baked into the static JS. Empty ⇒ /api/ntfy returns 204 and
	// the PWA skips subscription (voice-only, as before).
	ntfyWS := flag.String("ntfy", "", "ntfy WebSocket subscribe URL served to the PWA (e.g. wss://host/topic/ws?auth=...)")
	// coreSock: mavend's IPC socket. When set, /api/signal writes presence
	// facts through CoreAPI (page heartbeat from the PWA, desk_active from a PC
	// script). Empty ⇒ /api/signal returns 503 and presence stays unfed.
	coreSock := flag.String("core", "", "mavend IPC socket path for presence-signal ingest (empty = disabled)")
	flag.Parse()

	var core ipc.CoreAPI
	if *coreSock != "" {
		c, err := ipc.Dial(*coreSock)
		if err != nil {
			log.Fatalf("dial core %s: %v", *coreSock, err)
		}
		defer c.Close()
		core = c
	}

	mux := http.NewServeMux()

	sub, err := fs.Sub(staticFiles, "static")
	if err != nil {
		log.Fatalf("static fs: %v", err)
	}
	mux.Handle("/", noCache(http.FileServer(http.FS(sub))))

	mux.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
		handleWS(w, r, *voiceAddr)
	})
	mux.HandleFunc("/api/ptt", func(w http.ResponseWriter, r *http.Request) {
		handlePTT(w, r, *voiceAddr)
	})
	mux.HandleFunc("/api/ping", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("pong"))
	})
	mux.HandleFunc("/api/ntfy", func(w http.ResponseWriter, r *http.Request) {
		if *ntfyWS == "" {
			w.WriteHeader(http.StatusNoContent) // not configured → PWA skips
			return
		}
		w.Header().Set("Content-Type", "text/plain")
		w.Write([]byte(*ntfyWS))
	})
	mux.HandleFunc("/api/signal", func(w http.ResponseWriter, r *http.Request) {
		handleSignal(w, r, core)
	})
	mux.HandleFunc("/dash", func(w http.ResponseWriter, r *http.Request) {
		handleDash(w, r, core)
	})
	// /tools — the authed enable surface. maven proposes acts she can't run;
	// this page is where a human reviews and enables them (proposed→enabled).
	// Enabling is the boundary-moving act (maven.md), so it lives ONLY here,
	// behind wg+nginx+auth — never the voice/chat path.
	mux.HandleFunc("/tools", func(w http.ResponseWriter, r *http.Request) {
		handleTools(w, r, core)
	})

	srv := &http.Server{Addr: *addr, Handler: mux}

	go func() {
		sig := make(chan os.Signal, 1)
		signal.Notify(sig, os.Interrupt)
		<-sig
		log.Println("shutting down...")
		srv.Close()
	}()

	log.Printf("mavweb listening on %s, voice → %s", *addr, *voiceAddr)
	if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
		log.Fatal(err)
	}
}

func handleWS(w http.ResponseWriter, r *http.Request, voiceAddr string) {
	conn, err := websocket.Accept(w, r, &websocket.AcceptOptions{
		OriginPatterns: []string{"*"},
	})
	if err != nil {
		log.Printf("ws accept: %v", err)
		return
	}
	defer conn.Close(websocket.StatusNormalClosure, "bye")

	ctx := r.Context()

	var d net.Dialer
	tc, err := d.DialContext(ctx, "tcp", voiceAddr)
	if err != nil {
		log.Printf("dial voice: %v", err)
		writeWSErr(conn, ctx, "voice unavailable")
		return
	}
	defer tc.Close()

	for {
		_, msg, err := conn.Read(ctx)
		if err != nil {
			log.Printf("ws read: %v", err)
			return
		}
		if len(msg) < 4 {
			log.Printf("ws msg too short (%d bytes)", len(msg))
			continue
		}

		log.Printf("ws got %d bytes from client", len(msg))
		pcm := audio.Audio{Format: audio.PCM16kMono, Bytes: msg}

		req := voice.Request{
			ID:     uint64(time.Now().UnixNano()),
			Method: voice.MethodPushToTalk,
			Params: mustMarshal(voice.PushToTalkReq{
				Audio:   pcm,
				Lang:    "mixed",
				Surface: voice.SurfacePCClient,
			}),
		}

		if err := writeFrame(tc, &req); err != nil {
			log.Printf("write voice req: %v", err)
			return
		}

		// Read frames until we get the matching Response (handling any interleaved Pushes)
		for {
			resp, push, err := readOneFrame(tc)
			if err != nil {
				log.Printf("read voice: %v", err)
				return
			}
			if push != nil {
				data, _ := json.Marshal(push)
				conn.Write(ctx, websocket.MessageText, data)
				continue
			}
			if resp.Error != nil {
				writeWSErr(conn, ctx, resp.Error.Message)
				break
			}
			var pttResp voice.PushToTalkResp
			if err := json.Unmarshal(resp.Result, &pttResp); err != nil {
				log.Printf("unmarshal resp: %v", err)
				break
			}
			if pttResp.ReplyText != "" {
				conn.Write(ctx, websocket.MessageText, []byte(pttResp.ReplyText))
			}
			if len(pttResp.ReplyAudio.Bytes) > 0 {
				conn.Write(ctx, websocket.MessageBinary, pttResp.ReplyAudio.Bytes)
			}
			break
		}
	}
}

// handleSignal ingests one presence signal and writes a fresh fact through
// CoreAPI. The fact's timestamp (now) is all the presence scorer reads; value
// is a marker. Only allowlisted keys are accepted (see presenceSignals).
func handleSignal(w http.ResponseWriter, r *http.Request, core ipc.CoreAPI) {
	if r.Method != http.MethodPost {
		http.Error(w, "POST only", http.StatusMethodNotAllowed)
		return
	}
	if core == nil {
		http.Error(w, "presence ingest disabled (no -core)", http.StatusServiceUnavailable)
		return
	}
	key := r.URL.Query().Get("key")
	source, ok := presenceSignals[key]
	if !ok {
		http.Error(w, "unknown signal key", http.StatusBadRequest)
		return
	}
	// kind=env: an observation about the device/surface, NOT a self-fact — a
	// passive signal never writes truth about you (spec), it only feeds
	// presence. confidence 1.0: the reading ("input happened") is certain;
	// presence applies its own per-signal weight/decay on top.
	if _, err := core.WriteFact(r.Context(), ipc.WriteFactReq{
		Ts:         time.Now(),
		Kind:       "env",
		Key:        key,
		Value:      `"active"`,
		Source:     source,
		Confidence: 1.0,
	}); err != nil {
		log.Printf("signal %s: %v", key, err)
		http.Error(w, "write failed", http.StatusBadGateway)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func handleDash(w http.ResponseWriter, r *http.Request, core ipc.CoreAPI) {
	if core == nil {
		http.Error(w, "dash disabled (no -core)", http.StatusServiceUnavailable)
		return
	}
	ctx := r.Context()
	pres, err1 := core.Presence(ctx)
	facts, err2 := core.RecentFacts(ctx, 50)
	nudges, err3 := core.RecentNudges(ctx, 50)
	notes, err4 := core.RecentNotes(ctx, 50)
	if err := cmp.Or(err1, err2, err3, err4); err != nil {
		log.Printf("dash: %v", err)
		http.Error(w, "core read failed", http.StatusBadGateway)
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := dashTmpl.Execute(w, struct {
		Presence ipc.Presence
		Facts    []ipc.Fact
		Nudges   []ipc.Nudge
		Notes    []ipc.Note
	}{pres, facts, nudges, notes}); err != nil {
		log.Printf("dash render: %v", err)
	}
}

// toolsTmpl — the enable surface. Server-rendered, no JS: a plain HTML form
// POSTs back to /tools to enable a proposal. html/template escapes tool names +
// utterances (they came from voice STT — untrusted text).
var toolsTmpl = template.Must(template.New("tools").Funcs(template.FuncMap{
	"join": strings.Join,
}).Parse(toolsHTML))

const toolsHTML = `<!doctype html><meta charset=utf-8><title>maven · tools</title>
<style>body{font:15px system-ui;margin:2rem;max-width:52rem}h2{margin-top:2rem}
table{border-collapse:collapse;width:100%}td,th{border:1px solid #ccc;padding:.4rem .6rem;text-align:left}
input[type=text]{width:22rem}code{background:#f4f4f4;padding:.1rem .3rem}
.d{color:#b00}.msg{background:#efe;border:1px solid #6c6;padding:.5rem;margin:1rem 0}</style>
<h1>maven · tools</h1>
{{if .Msg}}<div class=msg>{{.Msg}}</div>{{end}}
<h2>proposed <small>({{len .Proposed}})</small></h2>
{{if .Proposed}}<p>maven drafted these from acts she couldn't run. Fill the command (argv, space-separated) and enable.</p>
<table><tr><th>name</th><th>from utterance</th><th>enable as</th></tr>
{{range .Proposed}}<tr>
<td><code>{{.Name}}</code></td><td>{{.Utterance}}</td>
<td><form method=post action=/tools>
<input type=hidden name=name value="{{.Name}}">
<input type=text name=cmd placeholder="systemctl restart" required>
<label><input type=checkbox name=destructive> destructive</label>
<button>enable</button></form></td>
</tr>{{end}}</table>
{{else}}<p>none pending.</p>{{end}}
<h2>enabled <small>({{len .Enabled}})</small></h2>
{{if .Enabled}}<table><tr><th>name</th><th>command</th><th></th></tr>
{{range .Enabled}}<tr><td><code>{{.Name}}</code></td><td><code>{{join .Cmd " "}}</code></td>
<td>{{if .Destructive}}<span class=d>destructive</span>{{end}}</td></tr>{{end}}</table>
{{else}}<p>none enabled.</p>{{end}}
`

// handleTools serves the enable surface (GET) and applies an enable (POST).
// POST fields: name, cmd (space-separated argv), destructive (checkbox). cmd is
// whitespace-split — argv with embedded spaces isn't supported (ponytail: no
// shell-word parsing; the box owner controls this input, quote a wrapper script
// if an arg needs spaces).
func handleTools(w http.ResponseWriter, r *http.Request, core ipc.CoreAPI) {
	if core == nil {
		http.Error(w, "tools disabled (no -core)", http.StatusServiceUnavailable)
		return
	}
	ctx := r.Context()
	var msg string
	if r.Method == http.MethodPost {
		name := strings.TrimSpace(r.FormValue("name"))
		cmd := strings.Fields(r.FormValue("cmd"))
		destructive := r.FormValue("destructive") != ""
		if name == "" || len(cmd) == 0 {
			http.Error(w, "name and cmd required", http.StatusBadRequest)
			return
		}
		if err := core.EnableTool(ctx, name, cmd, destructive, time.Now()); err != nil {
			log.Printf("tools: enable %q: %v", name, err)
			http.Error(w, "enable failed: "+err.Error(), http.StatusBadGateway)
			return
		}
		msg = "enabled " + name
	}
	proposed, err1 := core.ListTools(ctx, "proposed")
	enabled, err2 := core.ListTools(ctx, "enabled")
	if err := cmp.Or(err1, err2); err != nil {
		log.Printf("tools: %v", err)
		http.Error(w, "core read failed", http.StatusBadGateway)
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := toolsTmpl.Execute(w, struct {
		Msg      string
		Proposed []ipc.Tool
		Enabled  []ipc.Tool
	}{msg, proposed, enabled}); err != nil {
		log.Printf("tools render: %v", err)
	}
}

func writeWSErr(conn *websocket.Conn, ctx context.Context, msg string) {
	conn.Write(ctx, websocket.MessageText, []byte(`{"error":"`+msg+`"}`))
}

func writeFrame(w io.Writer, v any) error {
	body, err := json.Marshal(v)
	if err != nil {
		return fmt.Errorf("marshal: %w", err)
	}
	const maxFrame = 64 << 20
	if len(body) > maxFrame {
		return fmt.Errorf("frame too large: %d", len(body))
	}
	var hdr [4]byte
	binary.BigEndian.PutUint32(hdr[:], uint32(len(body)))
	if _, err := w.Write(hdr[:]); err != nil {
		return err
	}
	_, err = w.Write(body)
	return err
}

func readFrame(r io.Reader, v any) error {
	var hdr [4]byte
	if _, err := io.ReadFull(r, hdr[:]); err != nil {
		return err
	}
	n := binary.BigEndian.Uint32(hdr[:])
	const maxFrame = 64 << 20
	if n > maxFrame {
		return fmt.Errorf("frame too large: %d", n)
	}
	buf := make([]byte, n)
	if _, err := io.ReadFull(r, buf); err != nil {
		return err
	}
	return json.Unmarshal(buf, v)
}

func readOneFrame(r io.Reader) (*voice.Response, *voice.Push, error) {
	var raw struct {
		ID     uint64          `json:"id"`
		Result json.RawMessage `json:"r,omitempty"`
		Error  *voice.RpcError `json:"e,omitempty"`
		Kind   voice.PushKind  `json:"kind,omitempty"`
		Params json.RawMessage `json:"p,omitempty"`
	}
	if err := readFrame(r, &raw); err != nil {
		return nil, nil, err
	}
	if raw.Kind != "" && raw.ID == 0 {
		return nil, &voice.Push{Kind: raw.Kind, Params: raw.Params}, nil
	}
	return &voice.Response{ID: raw.ID, Result: raw.Result, Error: raw.Error}, nil, nil
}

func handlePTT(w http.ResponseWriter, r *http.Request, voiceAddr string) {
	if r.Method != http.MethodPost {
		http.Error(w, "POST only", 405)
		return
	}
	body, err := io.ReadAll(r.Body)
	if err != nil {
		http.Error(w, err.Error(), 400)
		return
	}
	if len(body) < 4 {
		http.Error(w, "too short", 400)
		return
	}

	log.Printf("ptt got %d bytes from client", len(body))

	pcm := audio.Audio{Format: audio.PCM16kMono, Bytes: body}

	var d net.Dialer
	tc, err := d.DialContext(r.Context(), "tcp", voiceAddr)
	if err != nil {
		log.Printf("ptt dial voice: %v", err)
		http.Error(w, "voice unavailable", 503)
		return
	}
	defer tc.Close()

	req := voice.Request{
		ID:     uint64(time.Now().UnixNano()),
		Method: voice.MethodPushToTalk,
		Params: mustMarshal(voice.PushToTalkReq{
			Audio:   pcm,
			Lang:    "mixed",
			Surface: voice.SurfacePCClient,
		}),
	}
	if err := writeFrame(tc, &req); err != nil {
		log.Printf("ptt write: %v", err)
		http.Error(w, err.Error(), 500)
		return
	}

	for {
		resp, push, err := readOneFrame(tc)
		if err != nil {
			log.Printf("ptt read: %v", err)
			http.Error(w, err.Error(), 500)
			return
		}
		if push != nil {
			continue
		}
		if resp.Error != nil {
			http.Error(w, resp.Error.Message, 500)
			return
		}
		var pttResp voice.PushToTalkResp
		if err := json.Unmarshal(resp.Result, &pttResp); err != nil {
			http.Error(w, err.Error(), 500)
			return
		}
		w.Header().Set("Content-Type", "audio/l16;rate=16000;channels=1")
		w.Header().Set("X-Reply-Text", url.QueryEscape(pttResp.ReplyText))
		w.Write(pttResp.ReplyAudio.Bytes)
		return
	}
}

func mustMarshal(v any) json.RawMessage {
	b, err := json.Marshal(v)
	if err != nil {
		panic(err)
	}
	return b
}