package api

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"time"

	"github.com/google/uuid"
	"go.temporal.io/sdk/client"

	"github.com/rockliang/poimen/workflows/internal/routing"
	"github.com/rockliang/poimen/workflows/pkg/db"
)

// WorkflowNode matches frontend node type
type WorkflowNode struct {
	ID       string                 `json:"id"`
	Type     string                 `json:"type"` // "activity", "start", "end"
	Position map[string]interface{} `json:"position"`
	Data     struct {
		Label    string                 `json:"label"`
		Activity string                 `json:"activity"`
		Config   map[string]interface{} `json:"config"`
	} `json:"data"`
}

// WorkflowEdge matches frontend edge type
type WorkflowEdge struct {
	ID     string                 `json:"id"`
	Source string                 `json:"source"`
	Target string                 `json:"target"`
	Data   map[string]interface{} `json:"data,omitempty"`
}

// WorkflowDef is the request body for creating/updating workflows
type WorkflowDef struct {
	Name        string          `json:"name"`
	Description string          `json:"description"`
	Nodes       []WorkflowNode  `json:"nodes"`
	Edges       []WorkflowEdge  `json:"edges"`
	Status      string          `json:"status"` // "draft", "active"
}

// WorkflowResponse is the workflow with metadata
type WorkflowResponse struct {
	ID          string          `json:"id"`
	Name        string          `json:"name"`
	Description string          `json:"description"`
	Status      string          `json:"status"`
	Version     int             `json:"version"`
	Nodes       []WorkflowNode  `json:"nodes"`
	Edges       []WorkflowEdge  `json:"edges"`
	CreatedAt   string          `json:"createdAt"`
	UpdatedAt   string          `json:"updatedAt"`
	CreatedBy   string          `json:"createdBy"`
}

// ExecutionRequest is the request to execute a workflow
type ExecutionRequest struct {
	Inputs map[string]interface{} `json:"inputs"`
}

// ExecutionResponse is the execution result
type ExecutionResponse struct {
	ID           string                 `json:"id"`
	WorkflowID   string                 `json:"workflowId"`
	Status       string                 `json:"status"` // "pending", "running", "success", "failed"
	StartedAt    string                 `json:"startedAt"`
	CompletedAt  string                 `json:"completedAt,omitempty"`
	Inputs       map[string]interface{} `json:"inputs"`
	Outputs      map[string]interface{} `json:"outputs,omitempty"`
	Errors       []string               `json:"errors,omitempty"`
	Logs         []ExecutionLog         `json:"logs"`
}

// ExecutionLog is a log entry from execution
type ExecutionLog struct {
	Timestamp string `json:"timestamp"`
	NodeID    string `json:"nodeId"`
	Level     string `json:"level"` // "info", "warn", "error"
	Message   string `json:"message"`
}

// WorkflowAPI handles workflow endpoints
type WorkflowAPI struct {
	db             *db.DB
	temporalClient client.Client
	logger         *log.Logger
	customerID     string // TODO: Extract from JWT token
}

// NewWorkflowAPI creates new API handler
func NewWorkflowAPI(database *db.DB, tc client.Client, logger *log.Logger) *WorkflowAPI {
	return &WorkflowAPI{
		db:             database,
		temporalClient: tc,
		logger:         logger,
		customerID:     "default-customer", // TODO: From auth context
	}
}

// CreateWorkflow handles POST /workflows
func (api *WorkflowAPI) CreateWorkflow(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	var req WorkflowDef
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, fmt.Sprintf("Invalid request: %v", err), http.StatusBadRequest)
		return
	}

	if req.Name == "" {
		http.Error(w, "Workflow name required", http.StatusBadRequest)
		return
	}

	// Create workflow in database
	id := uuid.New().String()
	now := time.Now()

	// Convert nodes and edges to JSONB
	nodesJSON, err := json.Marshal(req.Nodes)
	if err != nil {
		http.Error(w, fmt.Sprintf("Failed to marshal nodes: %v", err), http.StatusBadRequest)
		return
	}

	edgesJSON, err := json.Marshal(req.Edges)
	if err != nil {
		http.Error(w, fmt.Sprintf("Failed to marshal edges: %v", err), http.StatusBadRequest)
		return
	}

	status := req.Status
	if status == "" {
		status = "draft"
	}

	workflow := &db.Workflow{
		ID:          id,
		CustomerID:  api.customerID,
		Name:        req.Name,
		Description: req.Description,
		Status:      status,
		Version:     1,
		Nodes:       nodesJSON,
		Edges:       edgesJSON,
		CreatedBy:   "anonymous", // Use JWT claim in real implementation
		CreatedAt:   now,
		UpdatedAt:   now,
	}

	if err := api.db.SaveWorkflow(r.Context(), workflow); err != nil {
		api.logger.Printf("Failed to save workflow: %v", err)
		http.Error(w, "Failed to create workflow", http.StatusInternalServerError)
		return
	}

	response := WorkflowResponse{
		ID:          workflow.ID,
		Name:        workflow.Name,
		Description: workflow.Description,
		Status:      workflow.Status,
		Version:     workflow.Version,
		Nodes:       req.Nodes,
		Edges:       req.Edges,
		CreatedAt:   workflow.CreatedAt.Format(time.RFC3339),
		UpdatedAt:   workflow.UpdatedAt.Format(time.RFC3339),
		CreatedBy:   workflow.CreatedBy,
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(response)
}

// ListWorkflows handles GET /workflows
func (api *WorkflowAPI) ListWorkflows(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	page := 1
	limit := 10
	// Parse pagination params if needed

	workflows, err := api.db.ListWorkflows(r.Context(), api.customerID, limit, (page-1)*limit)
	if err != nil {
		api.logger.Printf("Failed to list workflows: %v", err)
		http.Error(w, "Failed to list workflows", http.StatusInternalServerError)
		return
	}

	list := make([]WorkflowResponse, 0)
	for _, wf := range workflows {
		var nodes []WorkflowNode
		var edges []WorkflowEdge

		json.Unmarshal(wf.Nodes, &nodes)
		json.Unmarshal(wf.Edges, &edges)

		list = append(list, WorkflowResponse{
			ID:          wf.ID,
			Name:        wf.Name,
			Description: wf.Description,
			Status:      wf.Status,
			Version:     wf.Version,
			Nodes:       nodes,
			Edges:       edges,
			CreatedAt:   wf.CreatedAt.Format(time.RFC3339),
			UpdatedAt:   wf.UpdatedAt.Format(time.RFC3339),
			CreatedBy:   wf.CreatedBy,
		})
	}

	response := map[string]interface{}{
		"workflows": list,
		"total":     len(list),
		"page":      page,
		"limit":     limit,
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(response)
}

// GetWorkflow handles GET /workflows/{id}
func (api *WorkflowAPI) GetWorkflow(w http.ResponseWriter, r *http.Request, id string) {
	if r.Method != http.MethodGet {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	workflow, err := api.db.FetchWorkflow(r.Context(), id, api.customerID)
	if err != nil {
		http.Error(w, "Workflow not found", http.StatusNotFound)
		return
	}

	var nodes []WorkflowNode
	var edges []WorkflowEdge

	json.Unmarshal(workflow.Nodes, &nodes)
	json.Unmarshal(workflow.Edges, &edges)

	response := WorkflowResponse{
		ID:          workflow.ID,
		Name:        workflow.Name,
		Description: workflow.Description,
		Status:      workflow.Status,
		Version:     workflow.Version,
		Nodes:       nodes,
		Edges:       edges,
		CreatedAt:   workflow.CreatedAt.Format(time.RFC3339),
		UpdatedAt:   workflow.UpdatedAt.Format(time.RFC3339),
		CreatedBy:   workflow.CreatedBy,
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(response)
}

// UpdateWorkflow handles PUT /workflows/{id}
func (api *WorkflowAPI) UpdateWorkflow(w http.ResponseWriter, r *http.Request, id string) {
	if r.Method != http.MethodPut {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	// Fetch existing workflow
	workflow, err := api.db.FetchWorkflow(r.Context(), id, api.customerID)
	if err != nil {
		http.Error(w, "Workflow not found", http.StatusNotFound)
		return
	}

	var req WorkflowDef
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, fmt.Sprintf("Invalid request: %v", err), http.StatusBadRequest)
		return
	}

	// Update fields
	if req.Name != "" {
		workflow.Name = req.Name
	}
	if req.Description != "" {
		workflow.Description = req.Description
	}
	if req.Nodes != nil {
		nodesJSON, _ := json.Marshal(req.Nodes)
		workflow.Nodes = nodesJSON
	}
	if req.Edges != nil {
		edgesJSON, _ := json.Marshal(req.Edges)
		workflow.Edges = edgesJSON
	}
	if req.Status != "" {
		workflow.Status = req.Status
	}

	workflow.Version++
	workflow.UpdatedAt = time.Now()

	if err := api.db.SaveWorkflow(r.Context(), workflow); err != nil {
		api.logger.Printf("Failed to update workflow: %v", err)
		http.Error(w, "Failed to update workflow", http.StatusInternalServerError)
		return
	}

	var nodes []WorkflowNode
	var edges []WorkflowEdge

	json.Unmarshal(workflow.Nodes, &nodes)
	json.Unmarshal(workflow.Edges, &edges)

	response := WorkflowResponse{
		ID:          workflow.ID,
		Name:        workflow.Name,
		Description: workflow.Description,
		Status:      workflow.Status,
		Version:     workflow.Version,
		Nodes:       nodes,
		Edges:       edges,
		CreatedAt:   workflow.CreatedAt.Format(time.RFC3339),
		UpdatedAt:   workflow.UpdatedAt.Format(time.RFC3339),
		CreatedBy:   workflow.CreatedBy,
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(response)
}

// DeleteWorkflow handles DELETE /workflows/{id}
func (api *WorkflowAPI) DeleteWorkflow(w http.ResponseWriter, r *http.Request, id string) {
	if r.Method != http.MethodDelete {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	if err := api.db.DeleteWorkflow(r.Context(), id, api.customerID); err != nil {
		http.Error(w, "Workflow not found", http.StatusNotFound)
		return
	}

	w.WriteHeader(http.StatusNoContent)
}

// ExecuteWorkflow handles POST /workflows/{id}/execute
func (api *WorkflowAPI) ExecuteWorkflow(w http.ResponseWriter, r *http.Request, id string) {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	workflow, err := api.db.FetchWorkflow(r.Context(), id, api.customerID)
	if err != nil {
		http.Error(w, "Workflow not found", http.StatusNotFound)
		return
	}

	var req ExecutionRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, fmt.Sprintf("Invalid request: %v", err), http.StatusBadRequest)
		return
	}

	// Unmarshal nodes and edges
	var nodes []WorkflowNode
	var edges []WorkflowEdge
	json.Unmarshal(workflow.Nodes, &nodes)
	json.Unmarshal(workflow.Edges, &edges)

	// Convert to workflow response for spec conversion
	workflowResp := &WorkflowResponse{
		ID:          workflow.ID,
		Name:        workflow.Name,
		Description: workflow.Description,
		Status:      workflow.Status,
		Version:     workflow.Version,
		Nodes:       nodes,
		Edges:       edges,
		CreatedBy:   workflow.CreatedBy,
	}

	// Convert nodes/edges to WorkflowSpec
	spec := api.nodesToWorkflowSpec(workflowResp, req.Inputs)

	// Execute via Temporal RoutingWorkflow
	execID := uuid.New().String()
	workflowOptions := client.StartWorkflowOptions{
		ID:        execID,
		TaskQueue: "default",
	}

	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	_, err = api.temporalClient.ExecuteWorkflow(ctx, workflowOptions, "RoutingWorkflow", spec)
	if err != nil {
		api.logger.Printf("Failed to execute workflow: %v", err)
		http.Error(w, fmt.Sprintf("Execution failed: %v", err), http.StatusInternalServerError)
		return
	}

	// Save execution to database
	inputsJSON, _ := json.Marshal(req.Inputs)
	now := time.Now()

	execution := &db.WorkflowExecution{
		ID:         execID,
		WorkflowID: id,
		CustomerID: api.customerID,
		TemporalID: execID,
		Status:     "running",
		Inputs:     inputsJSON,
		StartedAt:  now,
	}

	if err := api.db.SaveExecution(r.Context(), execution); err != nil {
		api.logger.Printf("Failed to save execution: %v", err)
		http.Error(w, "Failed to save execution", http.StatusInternalServerError)
		return
	}

	// Create execution response
	execResp := ExecutionResponse{
		ID:        execID,
		WorkflowID: id,
		Status:    "running",
		StartedAt: now.Format(time.RFC3339),
		Inputs:    req.Inputs,
		Outputs:   make(map[string]interface{}),
		Logs:      []ExecutionLog{},
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(execResp)
}

// GetExecution handles GET /executions/{id}
func (api *WorkflowAPI) GetExecution(w http.ResponseWriter, r *http.Request, id string) {
	if r.Method != http.MethodGet {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	execution, err := api.db.FetchExecution(r.Context(), id)
	if err != nil {
		http.Error(w, "Execution not found", http.StatusNotFound)
		return
	}

	// Get logs from database
	logs, err := api.db.FetchExecutionLogs(r.Context(), id)
	if err != nil {
		api.logger.Printf("Failed to fetch logs: %v", err)
	}

	execLogs := make([]ExecutionLog, 0)
	for _, log := range logs {
		execLogs = append(execLogs, ExecutionLog{
			Timestamp: log.LoggedAt.Format(time.RFC3339),
			NodeID:    log.NodeID,
			Level:     log.Level,
			Message:   log.Message,
		})
	}

	// Parse inputs/outputs
	var inputs map[string]interface{}
	var outputs map[string]interface{}
	json.Unmarshal(execution.Inputs, &inputs)
	if execution.Outputs != nil {
		json.Unmarshal(execution.Outputs, &outputs)
	}

	// Check Temporal workflow status
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	desc, err := api.temporalClient.DescribeWorkflowExecution(ctx, execution.TemporalID, "")
	status := execution.Status
	if err == nil && desc != nil {
		switch desc.Status.String() {
		case "RUNNING":
			status = "running"
		case "COMPLETED":
			status = "success"
		case "FAILED":
			status = "failed"
		}
	}

	completedAtStr := ""
	if execution.CompletedAt != nil {
		completedAtStr = execution.CompletedAt.Format(time.RFC3339)
	}

	execResp := ExecutionResponse{
		ID:          execution.ID,
		WorkflowID:  execution.WorkflowID,
		Status:      status,
		StartedAt:   execution.StartedAt.Format(time.RFC3339),
		CompletedAt: completedAtStr,
		Inputs:      inputs,
		Outputs:     outputs,
		Logs:        execLogs,
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(execResp)
}

// ListExecutions handles GET /workflows/{id}/executions
func (api *WorkflowAPI) ListExecutions(w http.ResponseWriter, r *http.Request, workflowID string) {
	if r.Method != http.MethodGet {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	// TODO: Implement query by workflow_id in database
	// For now, return empty list (needs DB method for filtering by workflow_id)
	list := make([]ExecutionResponse, 0)

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(list)
}

// nodesToWorkflowSpec converts frontend nodes/edges to routing.WorkflowSpec
func (api *WorkflowAPI) nodesToWorkflowSpec(wf *WorkflowResponse, inputs map[string]interface{}) *routing.WorkflowSpec {
	spec := &routing.WorkflowSpec{
		Name:   wf.Name,
		Input:  inputs,
		States: []routing.State{},
	}

	// Build states from nodes
	stateMap := make(map[string]*routing.State)

	// Create all states
	for _, node := range wf.Nodes {
		if node.Type == "activity" {
			state := &routing.State{
				Name:     node.ID,
				Type:     routing.StateTypeTask,
				Resource: node.Data.Activity,
				Parameters: node.Data.Config,
				End:      false,
			}
			stateMap[node.ID] = state
			spec.States = append(spec.States, *state)
		}
	}

	// Wire edges (transitions)
	for _, edge := range wf.Edges {
		if state, exists := stateMap[edge.Source]; exists {
			state.Next = edge.Target
		}
	}

	// Mark last state as End
	if len(spec.States) > 0 {
		// Find state with no outgoing edge
		for i := range spec.States {
			hasNext := false
			for _, edge := range wf.Edges {
				if edge.Source == spec.States[i].Name {
					hasNext = true
					break
				}
			}
			if !hasNext {
				spec.States[i].End = true
			}
		}
	}

	return spec
}

// QueryWorkflowGraph handles POST /workflows/{id}/query
func (api *WorkflowAPI) QueryWorkflowGraph(w http.ResponseWriter, r *http.Request, workflowID string) {
	ctx, cancel := context.WithTimeout(r.Context(), 60*time.Second)
	defer cancel()

	var req QueryWorkflowGraphRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid request body", http.StatusBadRequest)
		return
	}

	// Defaults
	if req.SearchType == "" {
		req.SearchType = "edges"
	}
	if req.ConfidenceFloor == 0 {
		req.ConfidenceFloor = 0.5
	}
	if req.TopK == 0 {
		req.TopK = 10
	}
	if req.MaxPathDepth == 0 {
		req.MaxPathDepth = 3
	}
	if req.RankingProfile == "" {
		req.RankingProfile = "default"
	}

	// Get latest version if not specified
	if req.Version == 0 {
		wf, err := api.db.GetWorkflow(ctx, workflowID)
		if err != nil {
			http.Error(w, "Workflow not found", http.StatusNotFound)
			return
		}
		req.Version = wf.Version
	}

	// Call temporal workflow
	run, err := api.temporalClient.ExecuteWorkflow(
		ctx,
		client.StartWorkflowOptions{
			ID:        fmt.Sprintf("graph-query-%s-v%d", workflowID, req.Version),
			TaskQueue: "poimen",
		},
		"WorkflowGraphQuery",
		map[string]interface{}{
			"workflow_id":       workflowID,
			"query":             req.Query,
			"search_type":       req.SearchType,
			"relation_type":     req.RelationType,
			"version":           req.Version,
			"confidence_floor":  req.ConfidenceFloor,
			"top_k":             req.TopK,
			"find_paths":        req.FindPaths,
			"target_node_id":    req.TargetNodeID,
			"max_path_depth":    req.MaxPathDepth,
			"ranking_profile":   req.RankingProfile,
			"include_reasoning": req.IncludeReasoning,
		},
	)
	if err != nil {
		api.logger.Printf("Failed to start workflow: %v", err)
		http.Error(w, "Failed to start query workflow", http.StatusInternalServerError)
		return
	}

	var result map[string]interface{}
	if err := run.Get(ctx, &result); err != nil {
		api.logger.Printf("Workflow execution failed: %v", err)
		http.Error(w, "Query execution failed", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(result)
}

// QueryWorkflowGraphRequest matches frontend payload
type QueryWorkflowGraphRequest struct {
	Query            string  `json:"query"`
	SearchType       string  `json:"search_type"`
	RelationType     string  `json:"relation_type"`
	Version          int     `json:"version"`
	ConfidenceFloor  float64 `json:"confidence_floor"`
	TopK             int     `json:"top_k"`
	FindPaths        bool    `json:"find_paths"`
	TargetNodeID     string  `json:"target_node_id"`
	MaxPathDepth     int     `json:"max_path_depth"`
	RankingProfile   string  `json:"ranking_profile"`
	IncludeReasoning bool    `json:"include_reasoning"`
}

// GetWorkflowRelationVersions handles GET /workflows/{id}/relations/{edge_id}/versions
func (api *WorkflowAPI) GetWorkflowRelationVersions(w http.ResponseWriter, r *http.Request, workflowID, edgeID string) {
	ctx, cancel := context.WithTimeout(r.Context(), 10*time.Second)
	defer cancel()

	// Query relation versions from DB
	versions, err := api.db.GetRelationVersions(ctx, workflowID, edgeID)
	if err != nil {
		api.logger.Printf("Failed to get relation versions: %v", err)
		http.Error(w, "Failed to fetch relation versions", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]interface{}{
		"workflow_id": workflowID,
		"edge_id":     edgeID,
		"versions":    versions,
		"total_count": len(versions),
	})
}