package handlers

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

	"github.com/gin-gonic/gin"

	"chat-switchboard/events"
	"chat-switchboard/models"
	"chat-switchboard/notifications"
	"chat-switchboard/sandbox"
	"chat-switchboard/store"
	"chat-switchboard/tools"
	"chat-switchboard/workflow"
)

// ── Workflow Instance Handler ───────────────
// Manages the runtime lifecycle of workflow channels: starting instances,
// advancing/rejecting stages, and querying status.

type WorkflowInstanceHandler struct {
	stores   store.Stores
	hub      *events.Hub
	notifSvc *notifications.Service
	runner   *sandbox.Runner
}

func NewWorkflowInstanceHandler(stores store.Stores, hub *events.Hub, notifSvc *notifications.Service, runner *sandbox.Runner) *WorkflowInstanceHandler {
	return &WorkflowInstanceHandler{stores: stores, hub: hub, notifSvc: notifSvc, runner: runner}
}

// ── Start ───────────────────────────────────

// Start creates a new workflow channel from a published workflow version.
// POST /api/v1/workflows/:id/start
func (h *WorkflowInstanceHandler) Start(c *gin.Context) {
	ctx := c.Request.Context()
	wfID := c.Param("id")
	userID := c.GetString("user_id")

	wf, err := h.stores.Workflows.GetByID(ctx, wfID)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "workflow not found"})
		return
	}
	if !wf.IsActive {
		c.JSON(http.StatusBadRequest, gin.H{"error": "workflow is not active"})
		return
	}

	ver, err := h.stores.Workflows.GetLatestVersion(ctx, wfID)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "workflow has no published version — publish first"})
		return
	}

	stages, err := h.stores.Workflows.ListStages(ctx, wfID)
	if err != nil || len(stages) == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "workflow has no stages"})
		return
	}

	// Create the workflow channel
	ch := &models.Channel{
		UserID:      userID,
		Title:       wf.Name,
		Description: wf.Description,
		Type:        "workflow",
		TeamID:      wf.TeamID,
	}
	if err := h.stores.Channels.Create(ctx, ch); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to create channel: " + err.Error()})
		return
	}

	// Set workflow-specific columns (not part of base Channel.Create)
	allowAnon := wf.EntryMode == "public_link"
	err = h.stores.Channels.SetWorkflowInstance(ctx, ch.ID, wfID, ver.VersionNumber, []byte("{}"), "active")
	if err != nil {
		log.Printf("Failed to set workflow columns on channel %s: %v", ch.ID, err)
	}
	_ = h.stores.Channels.Update(ctx, ch.ID, map[string]interface{}{
		"allow_anonymous": allowAnon,
		"ai_mode":         "auto",
	})

	// Add caller as channel owner
	_ = h.stores.Channels.AddParticipant(ctx, &models.ChannelParticipant{
		ChannelID:       ch.ID,
		ParticipantType: "user",
		ParticipantID:   userID,
		Role:            "owner",
	})

	// Bind stage 0 persona as participant
	firstStage := stages[0]
	if firstStage.PersonaID != nil {
		_ = h.stores.Channels.AddParticipant(ctx, &models.ChannelParticipant{
			ChannelID:       ch.ID,
			ParticipantType: "persona",
			ParticipantID:   *firstStage.PersonaID,
			Role:            "member",
		})
	}

	c.JSON(http.StatusCreated, gin.H{
		"channel_id":       ch.ID,
		"workflow_id":      wfID,
		"workflow_version": ver.VersionNumber,
		"current_stage":    0,
		"stage":            firstStage,
	})
}

// ── Status ──────────────────────────────────

// GetStatus returns the workflow state for a channel.
// GET /api/v1/channels/:id/workflow/status
func (h *WorkflowInstanceHandler) GetStatus(c *gin.Context) {
	channelID := c.Param("id")
	ws, err := h.stores.Channels.GetWorkflowStatus(c.Request.Context(), channelID)
	if err != nil || ws == nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "workflow channel not found"})
		return
	}
	c.JSON(http.StatusOK, ws)
}

// ── Advance ─────────────────────────────────

// Advance moves the workflow to the next stage.
// POST /api/v1/channels/:id/workflow/advance
func (h *WorkflowInstanceHandler) Advance(c *gin.Context) {
	ctx := c.Request.Context()
	channelID := c.Param("id")

	workflowID, currentStage, status, err := h.readWorkflowState(ctx, channelID)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "workflow channel not found"})
		return
	}
	if status != "active" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "workflow is " + status + ", cannot advance"})
		return
	}

	stages, err := h.stores.Workflows.ListStages(ctx, workflowID)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to load stages"})
		return
	}

	var body struct {
		Data json.RawMessage `json:"data,omitempty"`
	}
	_ = c.ShouldBindJSON(&body)

	mergedData := tools.MergeWorkflowStageData(ctx, h.stores.Channels, channelID, body.Data)
	nextStage, err := workflow.ResolveNextStage(stages, currentStage, json.RawMessage(mergedData))
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "routing error: " + err.Error()})
		return
	}

	if nextStage >= len(stages) {
		// Workflow complete
		err = h.stores.Channels.CompleteWorkflow(ctx, channelID, nextStage, json.RawMessage(mergedData))
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to complete workflow"})
			return
		}
		tools.CreateWorkflowStageNote(ctx, h.stores, channelID, currentStage, body.Data, "")

		// v0.27.0: Emit workflow.completed WS event
		h.emitWorkflowEvent("workflow.completed", channelID, map[string]any{
			"channel_id": channelID, "workflow_id": workflowID, "stage": nextStage,
		})

		// v0.27.0: on_complete chaining — trigger target workflow if configured
		h.triggerOnComplete(ctx, workflowID, channelID, mergedData)

		c.JSON(http.StatusOK, gin.H{"status": "completed", "current_stage": nextStage})
		return
	}

	// Advance to next stage
	err = h.stores.Channels.AdvanceWorkflowStage(ctx, channelID, nextStage, json.RawMessage(mergedData))
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to advance stage"})
		return
	}

	tools.CreateWorkflowStageNote(ctx, h.stores, channelID, currentStage, body.Data, "")

	// v0.35.0: Fire on_advance hook (can enrich stage_data)
	currentStageDef := stages[currentStage]
	if hookResult := FireOnAdvanceHook(ctx, h.stores, h.runner, currentStageDef.TransitionRules,
		channelID, currentStage, nextStage, json.RawMessage(mergedData)); hookResult != nil {
		if hookResult.Error != "" {
			log.Printf("[workflow] on_advance hook rejected: %s", hookResult.Error)
		} else if hookResult.EnrichedData != nil {
			_ = h.stores.Channels.AdvanceWorkflowStage(ctx, channelID, nextStage, hookResult.EnrichedData)
		}
	}

	nextStageDef := stages[nextStage]

	// Bind next persona (skip for form_only — no LLM needed)
	if nextStageDef.StageMode != models.StageModeFormOnly && nextStageDef.PersonaID != nil {
		alreadyIn, _ := h.stores.Channels.IsParticipant(ctx, channelID, "persona", *nextStageDef.PersonaID)
		if !alreadyIn {
			_ = h.stores.Channels.AddParticipant(ctx, &models.ChannelParticipant{
				ChannelID:       channelID,
				ParticipantType: "persona",
				ParticipantID:   *nextStageDef.PersonaID,
				Role:            "member",
			})
		}
	}

	// v0.27.0: Assignment + round-robin + WS notifications
	if nextStageDef.AssignmentTeamID != nil {
		assignmentID := tools.CreateWorkflowAssignment(ctx, h.stores, channelID, nextStage, *nextStageDef.AssignmentTeamID)

		// Round-robin auto-assignment if configured
		assignedTo := h.tryRoundRobin(ctx, nextStageDef, assignmentID)

		// Notify team members about new assignment
		h.notifyAssignment(ctx, *nextStageDef.AssignmentTeamID, channelID, nextStageDef.Name, assignedTo)
	}

	// v0.27.0: Emit workflow.advanced WS event
	h.emitWorkflowEvent("workflow.advanced", channelID, map[string]any{
		"channel_id": channelID, "workflow_id": workflowID,
		"stage": nextStage, "stage_name": nextStageDef.Name,
	})

	c.JSON(http.StatusOK, gin.H{
		"status":        "active",
		"current_stage": nextStage,
		"stage":         nextStageDef,
	})
}

// ── Reject ──────────────────────────────────

// Reject returns the workflow to the previous stage with a reason.
// POST /api/v1/channels/:id/workflow/reject
func (h *WorkflowInstanceHandler) Reject(c *gin.Context) {
	ctx := c.Request.Context()
	channelID := c.Param("id")

	var body struct {
		Reason string `json:"reason"`
	}
	if err := c.ShouldBindJSON(&body); err != nil || body.Reason == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "reason is required"})
		return
	}

	_, currentStage, status, err := h.readWorkflowState(ctx, channelID)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "workflow channel not found"})
		return
	}
	if status != "active" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "workflow is " + status + ", cannot reject"})
		return
	}
	if currentStage <= 0 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "cannot reject from the first stage"})
		return
	}

	prevStage := currentStage - 1
	err = h.stores.Channels.RejectWorkflowToStage(ctx, channelID, prevStage)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to reject stage"})
		return
	}

	// Persist rejection as system message
	if h.stores.Messages != nil {
		_ = h.stores.Messages.Create(ctx, &models.Message{
			ChannelID:       channelID,
			Role:            "system",
			Content:         "Stage rejected: " + body.Reason,
			ParticipantType: "user",
			ParticipantID:   c.GetString("user_id"),
		})
	}

	c.JSON(http.StatusOK, gin.H{
		"status":        "active",
		"current_stage": prevStage,
		"reason":        body.Reason,
	})
}

// ── Cancel (v0.37.15) ────────────────────────

// CancelInstance cancels a workflow instance and all its open assignments.
// POST /api/v1/channels/:id/workflow/cancel
func (h *WorkflowInstanceHandler) CancelInstance(c *gin.Context) {
	ctx := c.Request.Context()
	channelID := c.Param("id")
	userID := c.GetString("user_id")
	role, _ := c.Get("role")

	workflowID, _, status, err := h.readWorkflowState(ctx, channelID)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "workflow channel not found"})
		return
	}
	if status != "active" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "workflow is " + status + ", cannot cancel"})
		return
	}

	// Auth: instance owner, team admin, or global admin
	if role != "admin" {
		ch, err := h.stores.Channels.GetByID(ctx, channelID)
		if err != nil {
			c.JSON(http.StatusNotFound, gin.H{"error": "channel not found"})
			return
		}
		isOwner := ch.UserID == userID
		isTeamAdmin := false
		if ch.TeamID != nil && h.stores.Teams != nil {
			isTeamAdmin, _ = h.stores.Teams.IsTeamAdmin(ctx, *ch.TeamID, userID)
		}
		if !isOwner && !isTeamAdmin {
			c.JSON(http.StatusForbidden, gin.H{"error": "only instance owner, team admin, or global admin can cancel"})
			return
		}
	}

	// Cancel the workflow instance
	if err := h.stores.Channels.CancelWorkflow(ctx, channelID); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to cancel workflow"})
		return
	}

	// Cancel all open assignments
	cancelled, _ := h.stores.Workflows.CancelAssignmentsForChannel(ctx, channelID)

	// Emit WS event
	h.emitWorkflowEvent("workflow.cancelled", channelID, map[string]any{
		"channel_id":             channelID,
		"workflow_id":            workflowID,
		"cancelled_by":          userID,
		"assignments_cancelled": cancelled,
	})

	c.JSON(http.StatusOK, gin.H{
		"cancelled":              true,
		"channel_id":             channelID,
		"assignments_cancelled": cancelled,
	})
}

// CancelTeamInstance cancels a workflow instance via the team-admin monitor.
// POST /api/v1/teams/:teamId/workflows/monitor/instances/:channelId/cancel
func (h *WorkflowInstanceHandler) CancelTeamInstance(c *gin.Context) {
	teamID := c.Param("teamId")
	channelID := c.Param("channelId")
	userID := c.GetString("user_id")
	role, _ := c.Get("role")

	ctx := c.Request.Context()

	// Auth: team admin or global admin
	if role != "admin" {
		if h.stores.Teams == nil {
			c.JSON(http.StatusForbidden, gin.H{"error": "team admin access required"})
			return
		}
		isTA, _ := h.stores.Teams.IsTeamAdmin(ctx, teamID, userID)
		if !isTA {
			c.JSON(http.StatusForbidden, gin.H{"error": "team admin access required"})
			return
		}
	}

	// Verify the channel belongs to this team
	ch, err := h.stores.Channels.GetByID(ctx, channelID)
	if err != nil || ch.TeamID == nil || *ch.TeamID != teamID {
		c.JSON(http.StatusNotFound, gin.H{"error": "workflow instance not found for this team"})
		return
	}

	_, _, status, err := h.readWorkflowState(ctx, channelID)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "workflow channel not found"})
		return
	}
	if status != "active" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "workflow is " + status + ", cannot cancel"})
		return
	}

	if err := h.stores.Channels.CancelWorkflow(ctx, channelID); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to cancel workflow"})
		return
	}

	cancelled, _ := h.stores.Workflows.CancelAssignmentsForChannel(ctx, channelID)

	h.emitWorkflowEvent("workflow.cancelled", channelID, map[string]any{
		"channel_id":             channelID,
		"cancelled_by":          userID,
		"assignments_cancelled": cancelled,
	})

	c.JSON(http.StatusOK, gin.H{
		"cancelled":              true,
		"channel_id":             channelID,
		"assignments_cancelled": cancelled,
	})
}

// ── Helpers ─────────────────────────────────

func (h *WorkflowInstanceHandler) readWorkflowState(ctx context.Context, channelID string) (workflowID string, currentStage int, status string, err error) {
	ws, err := h.stores.Channels.GetWorkflowStatus(ctx, channelID)
	if err != nil || ws == nil {
		return "", 0, "", fmt.Errorf("workflow channel not found")
	}
	if ws.WorkflowID != nil {
		workflowID = *ws.WorkflowID
	}
	return workflowID, ws.CurrentStage, ws.Status, nil
}

// emitWorkflowEvent pushes a workflow event to all user participants in the channel.
// Uses PublishToUser (not room-scoped Bus.Publish) because room subscriptions are
// not yet wired on the client side. See websocket.md § Room Model.
func (h *WorkflowInstanceHandler) emitWorkflowEvent(label, channelID string, data map[string]any) {
	if h.hub == nil {
		return
	}
	payload, _ := json.Marshal(data)
	evt := events.Event{
		Label:   label,
		Payload: payload,
		Ts:      time.Now().UnixMilli(),
	}

	// Send to all user participants in the channel
	pids, err := h.stores.Channels.ListUserParticipantIDs(context.Background(), channelID, "")
	if err != nil {
		log.Printf("[ws] %s: failed to query participants for channel %s: %v", label, channelID[:min(8, len(channelID))], err)
		return
	}
	for _, uid := range pids {
		h.hub.PublishToUser(uid, evt)
	}
}

// triggerOnComplete checks if the workflow has an on_complete chain config
// and starts the target workflow if so.
func (h *WorkflowInstanceHandler) triggerOnComplete(ctx context.Context, workflowID, channelID, mergedData string) {
	// v0.27.3: Delegate to shared implementation (also handles webhooks)
	go tools.TriggerWorkflowOnComplete(ctx, h.stores, workflowID, channelID, mergedData)
}

// tryRoundRobin checks if the stage has auto_assign:"round_robin" in
// transition_rules and assigns the newly created assignment to the
// least-recently-assigned team member. Returns the assigned user ID or "".
func (h *WorkflowInstanceHandler) tryRoundRobin(ctx context.Context, stage models.WorkflowStage, assignmentID string) string {
	if assignmentID == "" || stage.AssignmentTeamID == nil {
		return ""
	}

	// Check transition_rules for auto_assign
	var rules struct {
		AutoAssign string `json:"auto_assign"`
	}
	if len(stage.TransitionRules) > 0 {
		_ = json.Unmarshal(stage.TransitionRules, &rules)
	}
	if rules.AutoAssign != "round_robin" {
		return ""
	}

	assignedTo, err := h.stores.Workflows.TryRoundRobin(ctx, *stage.AssignmentTeamID, assignmentID)
	if err != nil {
		log.Printf("[workflow] round-robin: failed to auto-assign %s: %v", assignmentID, err)
		return ""
	}
	if assignedTo != "" {
		log.Printf("[workflow] round-robin: auto-assigned %s to user %s", assignmentID, assignedTo)
	}
	return assignedTo
}

// notifyAssignment sends notifications to team members about a new workflow assignment.
func (h *WorkflowInstanceHandler) notifyAssignment(ctx context.Context, teamID, channelID, stageName, assignedTo string) {
	if h.notifSvc == nil || h.stores.Teams == nil {
		return
	}

	members, err := h.stores.Teams.ListMembers(ctx, teamID)
	if err != nil {
		return
	}

	for _, m := range members {
		title := "New workflow assignment"
		body := "Stage '" + stageName + "' needs review"
		if assignedTo != "" && m.UserID == assignedTo {
			title = "Workflow assigned to you"
			body = "Stage '" + stageName + "' has been assigned to you (round-robin)"
		}

		n := &models.Notification{
			UserID:       m.UserID,
			Type:         "workflow.assigned",
			Title:        title,
			Body:         body,
			ResourceType: models.ResourceTypeChannel,
			ResourceID:   channelID,
		}
		if err := h.notifSvc.Notify(ctx, n); err != nil {
			log.Printf("[workflow] notify assignment: %v", err)
		}
	}

	// Also emit targeted WS event for immediate UI update
	if h.hub != nil {
		payload, _ := json.Marshal(map[string]any{
			"channel_id": channelID, "team_id": teamID,
			"stage_name": stageName, "assigned_to": assignedTo,
		})
		for _, m := range members {
			h.hub.PublishToUser(m.UserID, events.Event{
				Label:   "workflow.assigned",
				Payload: payload,
				Ts:      time.Now().UnixMilli(),
			})
		}
	}
}

// createStageNote and mergeStageData are now in tools/workflow.go
// (shared between handler and workflow_advance tool).