package temporal

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strings"
	"time"
)

// PoimenHandler provides typed REST endpoints for Poimen workflows.
// Accessed via X-Service: poimen header through the ServiceAdapter dispatcher.
type PoimenHandler struct {
	handler *Handler
}

// NewPoimenHandler creates a new Poimen handler wrapping the Temporal handler.
func NewPoimenHandler(h *Handler) *PoimenHandler {
	return &PoimenHandler{handler: h}
}

// ServeHTTP routes based on X-Upstream-Path set by the dispatcher.
func (p *PoimenHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	path := r.Header.Get("X-Upstream-Path")
	if path == "" {
		path = r.URL.Path
	}

	switch {
	case path == "/v1/poimen/plan" && r.Method == http.MethodPost:
		p.handlePlan(w, r)
	case path == "/v1/poimen/execute" && r.Method == http.MethodPost:
		p.handleExecute(w, r)
	case path == "/v1/poimen/executions" && r.Method == http.MethodGet:
		p.handleListExecutions(w, r)
	case strings.HasPrefix(path, "/v1/poimen/executions/") && strings.HasSuffix(path, "/stream") && r.Method == http.MethodGet:
		p.handleStream(w, r)
	case strings.HasPrefix(path, "/v1/poimen/executions/") && strings.HasSuffix(path, "/signal") && r.Method == http.MethodPost:
		p.handleSignal(w, r)
	case strings.HasPrefix(path, "/v1/poimen/executions/") && strings.HasSuffix(path, "/history") && r.Method == http.MethodGet:
		p.handleHistory(w, r)
	case strings.HasPrefix(path, "/v1/poimen/executions/") && r.Method == http.MethodDelete:
		p.handleTerminate(w, r)
	case strings.HasPrefix(path, "/v1/poimen/executions/") && r.Method == http.MethodGet:
		p.handleDescribe(w, r)
	default:
		writeJSON(w, http.StatusNotFound, map[string]string{"error": "endpoint not found"})
	}
}

// extractWorkflowID extracts the workflow ID from paths like /v1/poimen/executions/{id}/...
func extractWorkflowID(path string) string {
	parts := strings.Split(strings.TrimPrefix(path, "/v1/poimen/executions/"), "/")
	if len(parts) > 0 && parts[0] != "" {
		return parts[0]
	}
	return ""
}

// PoimenWorkflowTypes maps Poimen workflow names to Temporal workflow types and task queues.
var PoimenWorkflowTypes = map[string]struct {
	WorkflowType string
	TaskQueue    string
}{
	"dag":          {WorkflowType: "DAGWorkflow", TaskQueue: "poimen-worker"},
	"orchestrator": {WorkflowType: "OrchestratorWorkflow", TaskQueue: "poimen-worker"},
	"routing":      {WorkflowType: "RoutingWorkflow", TaskQueue: "poimen-worker"},
}

// --- Plan ---

type PlanRequest struct {
	Message string                 `json:"message"`
	Context map[string]interface{} `json:"context,omitempty"`
}

func (p *PoimenHandler) handlePlan(w http.ResponseWriter, r *http.Request) {
	var req PlanRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON"})
		return
	}
	if req.Message == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "message is required"})
		return
	}

	// TODO: Call PlannerActivity directly (not via Temporal) for low latency.
	// For now, return a placeholder indicating the plan endpoint is wired.
	writeJSON(w, http.StatusNotImplemented, map[string]interface{}{
		"error":   "PlannerActivity not yet available",
		"message": req.Message,
		"context": req.Context,
		"hint":    "Depends on poimen-workflows#23 (PlannerActivity)",
	})
}

// --- Execute ---

type ExecuteRequest struct {
	WorkflowType string                 `json:"workflow_type"` // "dag", "orchestrator", "routing"
	Namespace    string                 `json:"namespace,omitempty"`
	Input        map[string]interface{} `json:"input"`
}

func (p *PoimenHandler) handleExecute(w http.ResponseWriter, r *http.Request) {
	var req ExecuteRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON"})
		return
	}

	if req.Namespace == "" {
		req.Namespace = "default"
	}

	wfType, ok := PoimenWorkflowTypes[req.WorkflowType]
	if !ok {
		writeJSON(w, http.StatusBadRequest, map[string]interface{}{
			"error":       fmt.Sprintf("unknown workflow_type: %s", req.WorkflowType),
			"valid_types": []string{"dag", "orchestrator", "routing"},
		})
		return
	}

	if p.handler.ops == nil {
		writeJSON(w, http.StatusServiceUnavailable, map[string]string{"error": "Temporal not available"})
		return
	}

	workflowID := fmt.Sprintf("poimen-%s-%d", req.WorkflowType, time.Now().UnixMilli())

	result, err := p.handler.ops.StartWorkflowExecution(
		r.Context(),
		req.Namespace,
		workflowID,
		wfType.WorkflowType,
		wfType.TaskQueue,
		req.Input,
	)
	if err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": fmt.Sprintf("failed to start workflow: %v", err)})
		return
	}

	writeJSON(w, http.StatusOK, result)
}

// --- List Executions ---

func (p *PoimenHandler) handleListExecutions(w http.ResponseWriter, r *http.Request) {
	if p.handler.ops == nil {
		writeJSON(w, http.StatusServiceUnavailable, map[string]string{"error": "Temporal not available"})
		return
	}

	namespace := r.URL.Query().Get("namespace")
	if namespace == "" {
		namespace = "default"
	}

	result, err := p.handler.ops.ListWorkflowExecutions(r.Context(), namespace, 100)
	if err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": fmt.Sprintf("failed to list: %v", err)})
		return
	}

	writeJSON(w, http.StatusOK, result)
}

// --- Describe ---

func (p *PoimenHandler) handleDescribe(w http.ResponseWriter, r *http.Request) {
	if p.handler.ops == nil {
		writeJSON(w, http.StatusServiceUnavailable, map[string]string{"error": "Temporal not available"})
		return
	}

	path := r.Header.Get("X-Upstream-Path")
	if path == "" {
		path = r.URL.Path
	}
	workflowID := extractWorkflowID(path)
	if workflowID == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id required in path"})
		return
	}

	namespace := r.URL.Query().Get("namespace")
	if namespace == "" {
		namespace = "default"
	}
	runID := r.URL.Query().Get("run_id")

	result, err := p.handler.ops.DescribeWorkflowExecution(r.Context(), namespace, workflowID, runID)
	if err != nil {
		writeJSON(w, http.StatusNotFound, map[string]string{"error": fmt.Sprintf("workflow not found: %v", err)})
		return
	}

	writeJSON(w, http.StatusOK, result)
}

// --- History ---

func (p *PoimenHandler) handleHistory(w http.ResponseWriter, r *http.Request) {
	if p.handler.ops == nil {
		writeJSON(w, http.StatusServiceUnavailable, map[string]string{"error": "Temporal not available"})
		return
	}

	path := r.Header.Get("X-Upstream-Path")
	if path == "" {
		path = r.URL.Path
	}
	workflowID := extractWorkflowID(path)
	if workflowID == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id required in path"})
		return
	}

	namespace := r.URL.Query().Get("namespace")
	if namespace == "" {
		namespace = "default"
	}
	runID := r.URL.Query().Get("run_id")

	result, err := p.handler.ops.GetWorkflowExecutionHistory(r.Context(), namespace, workflowID, runID)
	if err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": fmt.Sprintf("failed to get history: %v", err)})
		return
	}

	writeJSON(w, http.StatusOK, result)
}

// --- Signal ---

type SignalRequest struct {
	SignalName string                 `json:"signal_name"`
	Data       map[string]interface{} `json:"data,omitempty"`
	Namespace  string                 `json:"namespace,omitempty"`
}

func (p *PoimenHandler) handleSignal(w http.ResponseWriter, r *http.Request) {
	if p.handler.ops == nil {
		writeJSON(w, http.StatusServiceUnavailable, map[string]string{"error": "Temporal not available"})
		return
	}

	path := r.Header.Get("X-Upstream-Path")
	if path == "" {
		path = r.URL.Path
	}
	// Remove /signal suffix to get workflow ID
	cleanPath := strings.TrimSuffix(path, "/signal")
	workflowID := extractWorkflowID(cleanPath)
	if workflowID == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id required in path"})
		return
	}

	var req SignalRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON"})
		return
	}
	if req.SignalName == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "signal_name is required"})
		return
	}
	if req.Namespace == "" {
		req.Namespace = "default"
	}

	result, err := p.handler.ops.SignalWorkflowExecution(r.Context(), req.Namespace, workflowID, "", req.SignalName, req.Data)
	if err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": fmt.Sprintf("failed to signal: %v", err)})
		return
	}

	writeJSON(w, http.StatusOK, result)
}

// --- Terminate ---

func (p *PoimenHandler) handleTerminate(w http.ResponseWriter, r *http.Request) {
	if p.handler.ops == nil {
		writeJSON(w, http.StatusServiceUnavailable, map[string]string{"error": "Temporal not available"})
		return
	}

	path := r.Header.Get("X-Upstream-Path")
	if path == "" {
		path = r.URL.Path
	}
	workflowID := extractWorkflowID(path)
	if workflowID == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id required in path"})
		return
	}

	namespace := r.URL.Query().Get("namespace")
	if namespace == "" {
		namespace = "default"
	}

	result, err := p.handler.ops.TerminateWorkflowExecution(r.Context(), namespace, workflowID, "", "terminated via API")
	if err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": fmt.Sprintf("failed to terminate: %v", err)})
		return
	}

	writeJSON(w, http.StatusOK, result)
}

// --- Stream (delegate to existing SSE handler) ---

func (p *PoimenHandler) handleStream(w http.ResponseWriter, r *http.Request) {
	path := r.Header.Get("X-Upstream-Path")
	if path == "" {
		path = r.URL.Path
	}
	// Remove /stream suffix
	cleanPath := strings.TrimSuffix(path, "/stream")
	workflowID := extractWorkflowID(cleanPath)
	if workflowID == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "workflow_id required in path"})
		return
	}

	// Set query params for the SSE handler
	q := r.URL.Query()
	q.Set("workflow_id", workflowID)
	if q.Get("namespace") == "" {
		q.Set("namespace", "default")
	}
	r.URL.RawQuery = q.Encode()

	p.handler.StreamWorkflowEvents(w, r)
}

// --- Helpers ---

func writeJSON(w http.ResponseWriter, status int, data interface{}) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(data) //nolint:errcheck
}