package main

import (
	"crypto/subtle"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"strconv"
	"strings"
)

type API struct {
	cfg    *Config
	mgr    *Manager
	shares *ShareStore
	ntfy   *Ntfy
}

func (a *API) auth(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		tok := r.Header.Get("X-Api-Token")
		if tok == "" {
			if h := r.Header.Get("Authorization"); strings.HasPrefix(h, "Bearer ") {
				tok = strings.TrimPrefix(h, "Bearer ")
			}
		}
		if tok == "" {
			tok = r.URL.Query().Get("token") // SSE/EventSource + <img> links
		}
		if subtle.ConstantTimeCompare([]byte(tok), []byte(a.cfg.Token)) != 1 {
			jsonErr(w, http.StatusUnauthorized, "ogiltig eller saknad token")
			return
		}
		next(w, r)
	}
}

func jsonOut(w http.ResponseWriter, code int, v interface{}) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(code)
	json.NewEncoder(w).Encode(v)
}

func jsonErr(w http.ResponseWriter, code int, msg string) {
	jsonOut(w, code, map[string]string{"error": msg})
}

func readJSON(r *http.Request, v interface{}) error {
	defer r.Body.Close()
	return json.NewDecoder(io.LimitReader(r.Body, 1<<20)).Decode(v)
}

func (a *API) routes() *http.ServeMux {
	mux := http.NewServeMux()

	// oautentiserad läges-detektering: webbklienten är samma SPA för
	// lokal helmd och hub och avgör läget med det här svaret
	mux.HandleFunc("GET /api/mode", func(w http.ResponseWriter, r *http.Request) {
		jsonOut(w, 200, map[string]string{"mode": "local", "version": version})
	})

	mux.HandleFunc("GET /api/health", a.auth(func(w http.ResponseWriter, r *http.Request) {
		jsonOut(w, 200, map[string]interface{}{
			"ok": true, "version": version, "sessions": len(a.mgr.List()),
		})
	}))

	mux.HandleFunc("GET /api/sessions", a.auth(func(w http.ResponseWriter, r *http.Request) {
		jsonOut(w, 200, a.mgr.List())
	}))

	mux.HandleFunc("POST /api/sessions", a.auth(func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			Name  string `json:"name"`
			Cmd   string `json:"cmd"`
			Cwd   string `json:"cwd"`
			Adopt bool   `json:"adopt"`
			Tmux  string `json:"tmux"`
		}
		if err := readJSON(r, &req); err != nil {
			jsonErr(w, 400, err.Error())
			return
		}
		var (
			s   *SessionState
			err error
		)
		if req.Adopt {
			s, err = a.mgr.Adopt(req.Name, req.Tmux)
		} else {
			s, err = a.mgr.Create(req.Name, req.Cmd, req.Cwd)
		}
		if err != nil {
			jsonErr(w, 400, err.Error())
			return
		}
		jsonOut(w, 201, s)
	}))

	mux.HandleFunc("GET /api/sessions/{name}", a.auth(func(w http.ResponseWriter, r *http.Request) {
		s, ok := a.mgr.Get(r.PathValue("name"))
		if !ok {
			jsonErr(w, 404, "ingen sådan session")
			return
		}
		jsonOut(w, 200, s)
	}))

	mux.HandleFunc("DELETE /api/sessions/{name}", a.auth(func(w http.ResponseWriter, r *http.Request) {
		if err := a.mgr.Kill(r.PathValue("name")); err != nil {
			jsonErr(w, 404, err.Error())
			return
		}
		jsonOut(w, 200, map[string]bool{"killed": true})
	}))

	mux.HandleFunc("GET /api/sessions/{name}/screen", a.auth(func(w http.ResponseWriter, r *http.Request) {
		ansi := r.URL.Query().Get("ansi") == "1"
		history, _ := strconv.Atoi(r.URL.Query().Get("history"))
		screen, err := a.mgr.Screen(r.PathValue("name"), ansi, history)
		if err != nil {
			jsonErr(w, 404, err.Error())
			return
		}
		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
		io.WriteString(w, screen)
	}))

	mux.HandleFunc("POST /api/sessions/{name}/prompt", a.auth(func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			Text   string `json:"text"`
			Submit *bool  `json:"submit"`
		}
		if err := readJSON(r, &req); err != nil || req.Text == "" {
			jsonErr(w, 400, "JSON-kropp med \"text\" krävs")
			return
		}
		submit := req.Submit == nil || *req.Submit
		if err := a.mgr.Prompt(r.PathValue("name"), req.Text, submit); err != nil {
			jsonErr(w, 400, err.Error())
			return
		}
		jsonOut(w, 200, map[string]bool{"sent": true})
	}))

	mux.HandleFunc("GET /api/sessions/{name}/question", a.auth(func(w http.ResponseWriter, r *http.Request) {
		s, ok := a.mgr.Get(r.PathValue("name"))
		if !ok {
			jsonErr(w, 404, "ingen sådan session")
			return
		}
		jsonOut(w, 200, map[string]interface{}{"question": s.Question})
	}))

	mux.HandleFunc("POST /api/sessions/{name}/answer", a.auth(func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			Option int `json:"option"`
		}
		if err := readJSON(r, &req); err != nil {
			jsonErr(w, 400, err.Error())
			return
		}
		if err := a.mgr.Answer(r.PathValue("name"), req.Option); err != nil {
			jsonErr(w, 400, err.Error())
			return
		}
		jsonOut(w, 200, map[string]bool{"answered": true})
	}))

	mux.HandleFunc("POST /api/sessions/{name}/keys", a.auth(func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			Keys []string `json:"keys"`
		}
		if err := readJSON(r, &req); err != nil || len(req.Keys) == 0 {
			jsonErr(w, 400, "JSON-kropp med \"keys\": [\"Enter\", ...] krävs")
			return
		}
		if err := a.mgr.Keys(r.PathValue("name"), req.Keys); err != nil {
			jsonErr(w, 400, err.Error())
			return
		}
		jsonOut(w, 200, map[string]bool{"sent": true})
	}))

	// Mode: "cycle" sends the agent's mode-switch key (Shift+Tab in
	// agy/Claude Code). Arbitrary key sequences via /keys.
	mux.HandleFunc("POST /api/sessions/{name}/mode", a.auth(func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			Action string `json:"action"`
		}
		if err := readJSON(r, &req); err != nil {
			jsonErr(w, 400, err.Error())
			return
		}
		if req.Action != "cycle" {
			jsonErr(w, 400, "stödd action: \"cycle\"")
			return
		}
		if err := a.mgr.Keys(r.PathValue("name"), []string{"BTab"}); err != nil {
			jsonErr(w, 400, err.Error())
			return
		}
		jsonOut(w, 200, map[string]bool{"sent": true})
	}))

	mux.HandleFunc("GET /api/config", a.auth(func(w http.ResponseWriter, r *http.Request) {
		c := *a.cfg
		c.Token = "(dold — se konfigfilen)"
		jsonOut(w, 200, c)
	}))

	mux.HandleFunc("PUT /api/config", a.auth(func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			AgentCmd  *string     `json:"agent_cmd"`
			AgentArgs *[]string   `json:"agent_args"`
			Workdir   *string     `json:"workdir"`
			PollMs    *int        `json:"poll_ms"`
			Ntfy      *NtfyConfig `json:"ntfy"`
		}
		if err := readJSON(r, &req); err != nil {
			jsonErr(w, 400, err.Error())
			return
		}
		if req.AgentCmd != nil {
			a.cfg.AgentCmd = *req.AgentCmd
		}
		if req.AgentArgs != nil {
			a.cfg.AgentArgs = *req.AgentArgs
		}
		if req.Workdir != nil {
			a.cfg.Workdir = *req.Workdir
		}
		if req.PollMs != nil && *req.PollMs >= 100 {
			a.cfg.PollMs = *req.PollMs
		}
		if req.Ntfy != nil {
			a.cfg.Ntfy = *req.Ntfy
		}
		if err := a.cfg.Save(); err != nil {
			jsonErr(w, 500, err.Error())
			return
		}
		jsonOut(w, 200, map[string]bool{"saved": true})
	}))

	mux.HandleFunc("GET /api/shares", a.auth(func(w http.ResponseWriter, r *http.Request) {
		jsonOut(w, 200, a.shares.List())
	}))

	mux.HandleFunc("POST /api/shares", a.auth(func(w http.ResponseWriter, r *http.Request) {
		if err := r.ParseMultipartForm(64 << 20); err != nil {
			jsonErr(w, 400, "multipart-form med fältet \"file\" krävs: "+err.Error())
			return
		}
		f, hdr, err := r.FormFile("file")
		if err != nil {
			jsonErr(w, 400, "fältet \"file\" saknas")
			return
		}
		defer f.Close()
		sh, err := a.shares.Add(hdr.Filename, r.FormValue("note"), r.FormValue("session"), f)
		if err != nil {
			jsonErr(w, 400, err.Error())
			return
		}
		a.mgr.emit(Event{Type: "share", Data: sh})
		jsonOut(w, 201, sh)
	}))

	mux.HandleFunc("GET /api/shares/{id}", a.auth(func(w http.ResponseWriter, r *http.Request) {
		sh, err := a.shares.Get(r.PathValue("id"))
		if err != nil {
			jsonErr(w, 404, "ingen sådan delning")
			return
		}
		jsonOut(w, 200, sh)
	}))

	mux.HandleFunc("GET /api/shares/{id}/raw", a.auth(func(w http.ResponseWriter, r *http.Request) {
		sh, err := a.shares.Get(r.PathValue("id"))
		if err != nil {
			jsonErr(w, 404, "ingen sådan delning")
			return
		}
		if sh.Mime != "" {
			w.Header().Set("Content-Type", sh.Mime)
		}
		w.Header().Set("Content-Security-Policy", "sandbox allow-scripts") // shared HTML must not reach the API with our token
		http.ServeFile(w, r, a.shares.Path(sh))
	}))

	mux.HandleFunc("DELETE /api/shares/{id}", a.auth(func(w http.ResponseWriter, r *http.Request) {
		if err := a.shares.Delete(r.PathValue("id")); err != nil {
			jsonErr(w, 404, err.Error())
			return
		}
		jsonOut(w, 200, map[string]bool{"deleted": true})
	}))

	mux.HandleFunc("POST /api/notify", a.auth(func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			Topic    string `json:"topic"`
			Title    string `json:"title"`
			Message  string `json:"message"`
			Priority string `json:"priority"`
		}
		if err := readJSON(r, &req); err != nil || req.Message == "" {
			jsonErr(w, 400, "JSON-kropp med \"message\" krävs")
			return
		}
		if req.Topic == "" {
			req.Topic = a.cfg.Ntfy.Topic
		}
		if !a.cfg.topicAllowed(req.Topic) {
			jsonErr(w, 403, "topic inte i allowed_topics")
			return
		}
		if err := a.ntfy.Publish(req.Topic, req.Title, req.Message, req.Priority); err != nil {
			jsonErr(w, 502, err.Error())
			return
		}
		jsonOut(w, 200, map[string]bool{"published": true})
	}))

	mux.HandleFunc("GET /api/events", a.auth(func(w http.ResponseWriter, r *http.Request) {
		fl, ok := w.(http.Flusher)
		if !ok {
			jsonErr(w, 500, "streaming stöds inte")
			return
		}
		w.Header().Set("Content-Type", "text/event-stream")
		w.Header().Set("Cache-Control", "no-cache")
		ch := a.mgr.Subscribe()
		defer a.mgr.Unsubscribe(ch)
		fmt.Fprintf(w, "event: hello\ndata: {\"version\":%q}\n\n", version)
		fl.Flush()
		for {
			select {
			case <-r.Context().Done():
				return
			case ev := <-ch:
				data, _ := json.Marshal(ev)
				fmt.Fprintf(w, "event: %s\ndata: %s\n\n", ev.Type, data)
				fl.Flush()
			}
		}
	}))

	return mux
}

func serve(cfg *Config) error {
	if _, err := exec_LookPath("tmux"); err != nil {
		return fmt.Errorf("tmux hittas inte i PATH — helmd kräver tmux")
	}
	ntfy := &Ntfy{cfg: &cfg.Ntfy}
	mgr := NewManager(cfg, ntfy)
	shares, err := NewShareStore(cfg)
	if err != nil {
		return err
	}
	api := &API{cfg: cfg, mgr: mgr, shares: shares, ntfy: ntfy}
	mux := api.routes()
	if cfg.Hub.Enabled && cfg.Hub.URL != "" {
		startUplink(cfg, mux, mgr)
	}
	mountWeb(mux)
	log.Printf("helmd %s lyssnar på http://%s (token i %s)", version, cfg.Listen, cfg.path)
	return http.ListenAndServe(cfg.Listen, mux)
}