// Package handlers provides HTTP handlers for the rdev API.
package handlers

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"sync"
	"sync/atomic"
	"time"

	"github.com/go-chi/chi/v5"
	"github.com/orchard9/rdev/internal/executor"
	"github.com/orchard9/rdev/internal/projects"
	"github.com/orchard9/rdev/pkg/api"
)

// ProjectsHandler handles project-related endpoints.
type ProjectsHandler struct {
	registry *projects.Registry
	executor *executor.Executor
	streams  *streamManager
	cmdID    atomic.Uint64
}

// NewProjectsHandler creates a new projects handler.
func NewProjectsHandler() *ProjectsHandler {
	return &ProjectsHandler{
		registry: projects.NewRegistry("rdev"),
		executor: executor.New("rdev"),
		streams:  newStreamManager(),
	}
}

// Mount registers the projects routes.
func (h *ProjectsHandler) Mount(r api.Router) {
	r.Route("/projects", func(r chi.Router) {
		r.Get("/", h.List)
		r.Get("/{id}", h.Get)
		r.Post("/{id}/claude", h.RunClaude)
		r.Post("/{id}/shell", h.RunShell)
		r.Post("/{id}/git", h.RunGit)
		r.Get("/{id}/events", h.Events)
	})
}

// List returns all available projects.
// GET /projects
func (h *ProjectsHandler) List(w http.ResponseWriter, r *http.Request) {
	// Refresh status from K8s
	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()
	h.registry.RefreshStatus(ctx)

	projects := h.registry.List()
	api.WriteSuccess(w, r, projects)
}

// Get returns a specific project by ID.
// GET /projects/{id}
func (h *ProjectsHandler) Get(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")

	project, ok := h.registry.Get(id)
	if !ok {
		api.WriteNotFound(w, r, fmt.Sprintf("project not found: %s", id))
		return
	}

	// Refresh this project's status
	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()
	h.registry.RefreshStatus(ctx)

	api.WriteSuccess(w, r, project)
}

// ClaudeRequest is the request body for POST /projects/{id}/claude.
type ClaudeRequest struct {
	Prompt   string `json:"prompt"`
	StreamID string `json:"stream_id,omitempty"`
}

// RunClaude executes a Claude command in the project's claudebox.
// POST /projects/{id}/claude
func (h *ProjectsHandler) RunClaude(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")

	project, ok := h.registry.Get(id)
	if !ok {
		api.WriteNotFound(w, r, fmt.Sprintf("project not found: %s", id))
		return
	}

	var req ClaudeRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		api.WriteBadRequest(w, r, "invalid request body")
		return
	}

	if req.Prompt == "" {
		api.WriteBadRequest(w, r, "prompt is required")
		return
	}

	// Generate command ID
	cmdNum := h.cmdID.Add(1)
	cmdID := fmt.Sprintf("cmd-%s-%03d", id, cmdNum)
	if req.StreamID != "" {
		cmdID = req.StreamID
	}

	// Create the command
	cmd := &executor.Command{
		ID:        cmdID,
		PodName:   project.PodName,
		Type:      executor.CommandTypeClaude,
		Args:      []string{req.Prompt},
		StartedAt: time.Now(),
	}

	// Execute in background
	go h.executeCommand(cmd)

	result := map[string]any{
		"id":         cmdID,
		"project":    id,
		"type":       "claude",
		"status":     "running",
		"stream_url": fmt.Sprintf("/projects/%s/events?stream_id=%s", id, cmdID),
	}

	api.WriteCreated(w, r, result)
}

// ShellRequest is the request body for POST /projects/{id}/shell.
type ShellRequest struct {
	Command  string `json:"command"`
	StreamID string `json:"stream_id,omitempty"`
}

// RunShell executes a shell command in the project's claudebox.
// POST /projects/{id}/shell
func (h *ProjectsHandler) RunShell(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")

	project, ok := h.registry.Get(id)
	if !ok {
		api.WriteNotFound(w, r, fmt.Sprintf("project not found: %s", id))
		return
	}

	var req ShellRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		api.WriteBadRequest(w, r, "invalid request body")
		return
	}

	if req.Command == "" {
		api.WriteBadRequest(w, r, "command is required")
		return
	}

	// Generate command ID
	cmdNum := h.cmdID.Add(1)
	cmdID := fmt.Sprintf("cmd-%s-%03d", id, cmdNum)
	if req.StreamID != "" {
		cmdID = req.StreamID
	}

	// Create the command
	cmd := &executor.Command{
		ID:        cmdID,
		PodName:   project.PodName,
		Type:      executor.CommandTypeShell,
		Args:      []string{req.Command},
		StartedAt: time.Now(),
	}

	// Execute in background
	go h.executeCommand(cmd)

	result := map[string]any{
		"id":         cmdID,
		"project":    id,
		"type":       "shell",
		"status":     "running",
		"stream_url": fmt.Sprintf("/projects/%s/events?stream_id=%s", id, cmdID),
	}

	api.WriteCreated(w, r, result)
}

// GitRequest is the request body for POST /projects/{id}/git.
type GitRequest struct {
	Args     []string `json:"args"`
	StreamID string   `json:"stream_id,omitempty"`
}

// RunGit executes a git command in the project's claudebox.
// POST /projects/{id}/git
func (h *ProjectsHandler) RunGit(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")

	project, ok := h.registry.Get(id)
	if !ok {
		api.WriteNotFound(w, r, fmt.Sprintf("project not found: %s", id))
		return
	}

	var req GitRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		api.WriteBadRequest(w, r, "invalid request body")
		return
	}

	if len(req.Args) == 0 {
		api.WriteBadRequest(w, r, "args is required")
		return
	}

	// Generate command ID
	cmdNum := h.cmdID.Add(1)
	cmdID := fmt.Sprintf("cmd-%s-%03d", id, cmdNum)
	if req.StreamID != "" {
		cmdID = req.StreamID
	}

	// Create the command
	cmd := &executor.Command{
		ID:        cmdID,
		PodName:   project.PodName,
		Type:      executor.CommandTypeGit,
		Args:      req.Args,
		StartedAt: time.Now(),
	}

	// Execute in background
	go h.executeCommand(cmd)

	result := map[string]any{
		"id":         cmdID,
		"project":    id,
		"type":       "git",
		"status":     "running",
		"stream_url": fmt.Sprintf("/projects/%s/events?stream_id=%s", id, cmdID),
	}

	api.WriteCreated(w, r, result)
}

// executeCommand runs a command and streams output to subscribers.
func (h *ProjectsHandler) executeCommand(cmd *executor.Command) {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Minute)
	defer cancel()

	result := h.executor.Exec(ctx, cmd, func(stream, line string) {
		h.streams.Send(cmd.ID, "output", map[string]any{
			"line":   line,
			"stream": stream,
		})
	})

	// Send completion event
	h.streams.Send(cmd.ID, "complete", map[string]any{
		"exit_code":   result.ExitCode,
		"duration_ms": result.DurationMs,
	})

	// Clean up stream after a delay
	go func() {
		time.Sleep(30 * time.Second)
		h.streams.Close(cmd.ID)
	}()
}

// Events streams command output via Server-Sent Events.
// GET /projects/{id}/events
func (h *ProjectsHandler) Events(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	streamID := r.URL.Query().Get("stream_id")

	if !h.registry.Exists(id) {
		api.WriteNotFound(w, r, fmt.Sprintf("project not found: %s", id))
		return
	}

	// Set SSE headers
	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("Connection", "keep-alive")
	w.Header().Set("Access-Control-Allow-Origin", "*")

	flusher, ok := w.(http.Flusher)
	if !ok {
		http.Error(w, "SSE not supported", http.StatusInternalServerError)
		return
	}

	// Subscribe to events
	events := h.streams.Subscribe(streamID)
	defer h.streams.Unsubscribe(streamID, events)

	// Send initial connected event
	writeSSE(w, flusher, "connected", map[string]any{
		"project":   id,
		"stream_id": streamID,
	})

	// Stream events until client disconnects or stream closes
	ctx := r.Context()
	heartbeat := time.NewTicker(30 * time.Second)
	defer heartbeat.Stop()

	for {
		select {
		case <-ctx.Done():
			return
		case event, ok := <-events:
			if !ok {
				return
			}
			writeSSE(w, flusher, event.Type, event.Data)
			if event.Type == "complete" {
				return
			}
		case <-heartbeat.C:
			writeSSE(w, flusher, "heartbeat", map[string]any{
				"timestamp": time.Now().UTC().Format(time.RFC3339),
			})
		}
	}
}

// writeSSE writes a Server-Sent Event.
func writeSSE(w http.ResponseWriter, flusher http.Flusher, event string, data map[string]any) {
	dataBytes, _ := json.Marshal(data)
	fmt.Fprintf(w, "event: %s\n", event)
	fmt.Fprintf(w, "data: %s\n\n", dataBytes)
	flusher.Flush()
}

// streamManager manages SSE event streams.
type streamManager struct {
	mu      sync.RWMutex
	streams map[string][]chan streamEvent
}

type streamEvent struct {
	Type string
	Data map[string]any
}

func newStreamManager() *streamManager {
	return &streamManager{
		streams: make(map[string][]chan streamEvent),
	}
}

func (sm *streamManager) Subscribe(streamID string) chan streamEvent {
	sm.mu.Lock()
	defer sm.mu.Unlock()

	ch := make(chan streamEvent, 100)
	sm.streams[streamID] = append(sm.streams[streamID], ch)
	return ch
}

func (sm *streamManager) Unsubscribe(streamID string, ch chan streamEvent) {
	sm.mu.Lock()
	defer sm.mu.Unlock()

	channels := sm.streams[streamID]
	for i, c := range channels {
		if c == ch {
			sm.streams[streamID] = append(channels[:i], channels[i+1:]...)
			close(ch)
			break
		}
	}
}

func (sm *streamManager) Send(streamID, eventType string, data map[string]any) {
	sm.mu.RLock()
	defer sm.mu.RUnlock()

	for _, ch := range sm.streams[streamID] {
		select {
		case ch <- streamEvent{Type: eventType, Data: data}:
		default:
			// Channel full, skip
		}
	}
}

func (sm *streamManager) Close(streamID string) {
	sm.mu.Lock()
	defer sm.mu.Unlock()

	for _, ch := range sm.streams[streamID] {
		close(ch)
	}
	delete(sm.streams, streamID)
}