package main

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strconv"

	"powerpod/gotool/pb"
)

const otaMaxFirmwareSize = 2 * 1024 * 1024

type deadzoneAPIResponse struct {
	Deadzone      uint32 `json:"deadzone"`
	ClientID      uint32 `json:"client_id"`
	Success       bool   `json:"success"`
	SlavesUpdated uint32 `json:"slaves_updated"`
	Error         string `json:"error,omitempty"`
}

type deadzoneAPIRequest struct {
	Write      bool   `json:"write"`
	Deadzone   uint32 `json:"deadzone"`
	ClientID   uint32 `json:"client_id"`
	AllClients bool   `json:"all_clients"`
	// SlavesOnly: with all_clients, push to ESP-NOW slaves only (master BMA456 unchanged).
	SlavesOnly bool `json:"slaves_only"`
}

type unicastAPIRequest struct {
	ClientID uint32 `json:"client_id"`
	Seq      uint32 `json:"seq"`
}

type unicastAPIResponse struct {
	Success bool   `json:"success"`
	Seq     uint32 `json:"seq"`
	Error   string `json:"error,omitempty"`
}

type findMeAPIRequest struct {
	ClientID uint32 `json:"client_id"`
}

type findMeAPIResponse struct {
	Success  bool   `json:"success"`
	ClientID uint32 `json:"client_id,omitempty"`
	Error    string `json:"error,omitempty"`
}

type restartAPIRequest struct {
	ClientID uint32 `json:"client_id"`
}

type restartAPIResponse struct {
	Success  bool   `json:"success"`
	ClientID uint32 `json:"client_id,omitempty"`
	Error    string `json:"error,omitempty"`
}

type otaAPIResponse struct {
	Success       bool   `json:"success"`
	BytesWritten  uint32 `json:"bytes_written,omitempty"`
	TargetSlot    uint32 `json:"target_slot,omitempty"`
	Error         string `json:"error,omitempty"`
}

func mountServeAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub) {
	mux.HandleFunc("/api/deadzone", func(w http.ResponseWriter, r *http.Request) {
		switch r.Method {
		case http.MethodGet:
			serveDeadzoneGet(w, r, link)
		case http.MethodPost:
			serveDeadzonePost(w, r, link)
		default:
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		}
	})
	mux.HandleFunc("/api/unicast-test", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}
		serveUnicastTest(w, r, link)
	})
	mux.HandleFunc("/api/find-me", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}
		serveFindMe(w, r, link)
	})
	mux.HandleFunc("/api/restart", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}
		serveRestart(w, r, link)
	})
	mux.HandleFunc("/api/ota", func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
			return
		}
		serveOTAUpload(w, r, link, hub)
	})
}

func serveOTAUpload(w http.ResponseWriter, r *http.Request, link *managedSerial, hub *wsHub) {
	if err := r.ParseMultipartForm(otaMaxFirmwareSize); err != nil {
		writeJSON(w, http.StatusBadRequest, otaAPIResponse{Error: "invalid form"})
		return
	}
	file, _, err := r.FormFile("firmware")
	if err != nil {
		writeJSON(w, http.StatusBadRequest, otaAPIResponse{Error: "firmware file required"})
		return
	}
	defer file.Close()

	data, err := io.ReadAll(io.LimitReader(file, otaMaxFirmwareSize))
	if err != nil {
		writeJSON(w, http.StatusBadRequest, otaAPIResponse{Error: err.Error()})
		return
	}
	if len(data) == 0 {
		writeJSON(w, http.StatusBadRequest, otaAPIResponse{Error: "empty firmware"})
		return
	}

	var last OTAProgress
	err = runOTAUpload(link, data, func(p OTAProgress) {
		last = p
		if hub != nil {
			hub.broadcastRaw(p)
		}
	})
	if err != nil {
		if hub != nil {
			hub.broadcastRaw(OTAProgress{Type: "ota_progress", Phase: "error", Message: err.Error()})
		}
		writeJSON(w, http.StatusServiceUnavailable, otaAPIResponse{Error: err.Error()})
		return
	}
	writeJSON(w, http.StatusOK, otaAPIResponse{
		Success:      true,
		BytesWritten: last.Bytes,
		TargetSlot:   last.Slot,
	})
}

func serveDeadzoneGet(w http.ResponseWriter, r *http.Request, link *managedSerial) {
	clientID, err := parseUintQuery(r, "client_id", 0)
	if err != nil {
		writeJSON(w, http.StatusBadRequest, deadzoneAPIResponse{Error: err.Error()})
		return
	}
	resp, err := link.AccelDeadzone(&pb.AccelDeadzoneRequest{
		Write:    false,
		ClientId: clientID,
	})
	if err != nil {
		writeJSON(w, http.StatusServiceUnavailable, deadzoneAPIResponse{
			ClientID: clientID,
			Error:    err.Error(),
		})
		return
	}
	writeJSON(w, http.StatusOK, deadzoneAPIResponse{
		Deadzone: resp.GetDeadzone(),
		ClientID: resp.GetClientId(),
		Success:  resp.GetSuccess(),
	})
}

func serveDeadzonePost(w http.ResponseWriter, r *http.Request, link *managedSerial) {
	var body deadzoneAPIRequest
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		writeJSON(w, http.StatusBadRequest, deadzoneAPIResponse{Error: "invalid JSON"})
		return
	}
	if body.AllClients && body.SlavesOnly {
		updated, err := applyDeadzoneToSlaves(link, body.Deadzone)
		if err != nil {
			writeJSON(w, http.StatusServiceUnavailable, deadzoneAPIResponse{
				Error: err.Error(),
			})
			return
		}
		writeJSON(w, http.StatusOK, deadzoneAPIResponse{
			Deadzone:      body.Deadzone,
			Success:       updated > 0,
			SlavesUpdated: updated,
		})
		return
	}

	req := &pb.AccelDeadzoneRequest{
		Write:      true,
		Deadzone:   body.Deadzone,
		ClientId:   body.ClientID,
		AllClients: body.AllClients,
	}
	// client_id 0 without all_clients: master BMA456 only (same as CLI -client 0).
	resp, err := link.AccelDeadzone(req)
	if err != nil {
		writeJSON(w, http.StatusServiceUnavailable, deadzoneAPIResponse{
			ClientID: body.ClientID,
			Error:    err.Error(),
		})
		return
	}
	writeJSON(w, http.StatusOK, deadzoneAPIResponse{
		Deadzone:      resp.GetDeadzone(),
		ClientID:      resp.GetClientId(),
		Success:       resp.GetSuccess(),
		SlavesUpdated: resp.GetSlavesUpdated(),
	})
}

// applyDeadzoneToSlaves sets deadzone on each registered slave via per-client UART/ESP-NOW.
// Does not change the master's local BMA456 (use client_id 0 for that).
func applyDeadzoneToSlaves(link *managedSerial, deadzone uint32) (uint32, error) {
	clients, err := link.listClients()
	if err != nil {
		return 0, err
	}
	var updated uint32
	for _, c := range clients {
		resp, err := link.AccelDeadzone(&pb.AccelDeadzoneRequest{
			Write:    true,
			Deadzone: deadzone,
			ClientId: c.GetId(),
		})
		if err != nil {
			continue
		}
		if resp.GetSuccess() {
			updated++
		}
	}
	if len(clients) == 0 {
		return 0, fmt.Errorf("no slaves registered")
	}
	if updated == 0 {
		return 0, fmt.Errorf("deadzone not applied to any slave")
	}
	return updated, nil
}

func serveRestart(w http.ResponseWriter, r *http.Request, link *managedSerial) {
	var body restartAPIRequest
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		writeJSON(w, http.StatusBadRequest, restartAPIResponse{Error: "invalid JSON"})
		return
	}
	if err := link.Restart(body.ClientID); err != nil {
		writeJSON(w, http.StatusServiceUnavailable, restartAPIResponse{
			ClientID: body.ClientID,
			Error:    err.Error(),
		})
		return
	}
	writeJSON(w, http.StatusOK, restartAPIResponse{Success: true, ClientID: body.ClientID})
}

func serveFindMe(w http.ResponseWriter, r *http.Request, link *managedSerial) {
	var body findMeAPIRequest
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		writeJSON(w, http.StatusBadRequest, findMeAPIResponse{Error: "invalid JSON"})
		return
	}
	if err := link.FindMe(body.ClientID); err != nil {
		writeJSON(w, http.StatusServiceUnavailable, findMeAPIResponse{
			ClientID: body.ClientID,
			Error:    err.Error(),
		})
		return
	}
	writeJSON(w, http.StatusOK, findMeAPIResponse{Success: true, ClientID: body.ClientID})
}

func serveUnicastTest(w http.ResponseWriter, r *http.Request, link *managedSerial) {
	var body unicastAPIRequest
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		writeJSON(w, http.StatusBadRequest, unicastAPIResponse{Error: "invalid JSON"})
		return
	}
	if body.ClientID == 0 {
		writeJSON(w, http.StatusBadRequest, unicastAPIResponse{Error: "client_id required"})
		return
	}
	if body.Seq == 0 {
		body.Seq = 1
	}
	resp, err := link.EspnowUnicastTest(body.ClientID, body.Seq)
	if err != nil {
		writeJSON(w, http.StatusServiceUnavailable, unicastAPIResponse{Error: err.Error()})
		return
	}
	writeJSON(w, http.StatusOK, unicastAPIResponse{
		Success: resp.GetSuccess(),
		Seq:     resp.GetSeq(),
	})
}

func parseUintQuery(r *http.Request, key string, def uint32) (uint32, error) {
	s := r.URL.Query().Get(key)
	if s == "" {
		return def, nil
	}
	v, err := strconv.ParseUint(s, 10, 32)
	if err != nil {
		return 0, err
	}
	return uint32(v), nil
}

func writeJSON(w http.ResponseWriter, status int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(v)
}