// Package gateway provides real-time event handlers for the Control Center
// WebSocket client. Handlers process gateway events (sessions.changed,
// presence, agent.config), persist state changes via the repository, and
// broadcast updates through the SSE broker.
//
// Rule: DB update first, then SSE broadcast. This keeps REST API responses
// consistent with SSE events.
package gateway

import (
	"context"
	"encoding/json"
	"time"

	"code.cubecraftcreations.com/CubeCraft-Creations/Control-Center/go-backend/internal/models"
)

// ── Event payload types ──────────────────────────────────────────────────

// sessionChangedPayload represents a single session delta from a
// sessions.changed event.
type sessionChangedPayload struct {
	SessionKey     string `json:"sessionKey"`
	AgentID        string `json:"agentId"`
	Status         string `json:"status"` // running, streaming, done, error
	TotalTokens    int    `json:"totalTokens"`
	LastActivityAt string `json:"lastActivityAt"`
	CurrentTask    string `json:"currentTask"`
	TaskProgress   *int   `json:"taskProgress,omitempty"`
	TaskElapsed    string `json:"taskElapsed"`
	ErrorMessage   string `json:"errorMessage"`
}

// presencePayload represents a device presence update event.
type presencePayload struct {
	AgentID        string `json:"agentId"`
	Connected      *bool  `json:"connected,omitempty"`
	LastActivityAt string `json:"lastActivityAt"`
}

// agentConfigPayload represents an agent configuration change event.
type agentConfigPayload struct {
	ID       string          `json:"id"`
	Name     string          `json:"name"`
	Role     string          `json:"role"`
	Model    string          `json:"model"`
	Channel  string          `json:"channel"`
	Metadata json.RawMessage `json:"metadata"`
}

// ── Handler registration ─────────────────────────────────────────────────

// registerEventHandlers sets up all live event handlers on the WSClient.
// Called once after a successful handshake + initial sync.
func (c *WSClient) registerEventHandlers() {
	c.OnEvent("sessions.changed", c.handleSessionsChanged)
	c.OnEvent("presence", c.handlePresence)
	c.OnEvent("agent.config", c.handleAgentConfig)

	c.logger.Info("event handlers registered",
		"events", []string{"sessions.changed", "presence", "agent.config"})
}

// ── sessions.changed ─────────────────────────────────────────────────────

// handleSessionsChanged processes sessions.changed events from the gateway.
// The payload may be a single session object or an array of session deltas.
// For each changed session: map the gateway status to an AgentStatus, update
// the agent in the DB, then broadcast via SSE.
func (c *WSClient) handleSessionsChanged(payload json.RawMessage) {
	c.logger.Debug("handleSessionsChanged", "payload", string(payload))

	// Try array first, then single object
	var deltas []sessionChangedPayload
	if err := json.Unmarshal(payload, &deltas); err != nil || len(deltas) == 0 {
		var single sessionChangedPayload
		if err := json.Unmarshal(payload, &single); err != nil {
			c.logger.Warn("sessions.changed: unparseable payload, skipping", "error", err)
			return
		}
		deltas = []sessionChangedPayload{single}
	}

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	for _, d := range deltas {
		if d.AgentID == "" {
			c.logger.Debug("sessions.changed: skipping delta with empty agentId")
			continue
		}

		agentStatus := mapSessionStatus(d.Status)

		update := models.UpdateAgentRequest{
			Status: &agentStatus,
		}

		if d.CurrentTask != "" {
			update.CurrentTask = &d.CurrentTask
		}

		if d.TaskProgress != nil {
			update.TaskProgress = d.TaskProgress
		}

		if d.TaskElapsed != "" {
			update.TaskElapsed = &d.TaskElapsed
		}

		if d.ErrorMessage != "" {
			update.ErrorMessage = &d.ErrorMessage
		}

		// If session ended, clear task and progress
		if agentStatus == models.AgentStatusIdle {
			emptyTask := ""
			update.CurrentTask = &emptyTask
			zeroProg := 0
			update.TaskProgress = &zeroProg
		}

		// DB update first
		updated, err := c.agents.Update(ctx, d.AgentID, update)
		if err != nil {
			c.logger.Warn("sessions.changed: DB update failed",
				"agentId", d.AgentID, "error", err)
			continue
		}

		// Then SSE broadcast
		c.broker.Broadcast("agent.status", updated)
		if d.TaskProgress != nil || d.CurrentTask != "" {
			c.broker.Broadcast("agent.progress", updated)
		}

		c.logger.Debug("sessions.changed: agent updated",
			"agentId", d.AgentID, "status", string(agentStatus))
	}
}

// ── presence ─────────────────────────────────────────────────────────────

// handlePresence processes presence events from the gateway. Updates the
// agent's lastActivity and broadcasts status if the connection state changed.
func (c *WSClient) handlePresence(payload json.RawMessage) {
	c.logger.Debug("handlePresence", "payload", string(payload))

	var p presencePayload
	if err := json.Unmarshal(payload, &p); err != nil {
		c.logger.Warn("presence: unparseable payload, skipping", "error", err)
		return
	}

	if p.AgentID == "" {
		return
	}

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	update := models.UpdateAgentRequest{}

	// If device disconnected, set agent to idle
	if p.Connected != nil && !*p.Connected {
		idle := models.AgentStatusIdle
		update.Status = &idle
	}

	// DB update first (Update always bumps last_activity)
	updated, err := c.agents.Update(ctx, p.AgentID, update)
	if err != nil {
		c.logger.Warn("presence: DB update failed",
			"agentId", p.AgentID, "error", err)
		return
	}

	if p.LastActivityAt != "" {
		updated.LastActivity = p.LastActivityAt
	}

	// Then SSE broadcast
	c.broker.Broadcast("agent.status", updated)

	c.logger.Debug("presence: agent updated",
		"agentId", p.AgentID, "connected", p.Connected)
}

// ── agent.config ─────────────────────────────────────────────────────────

// handleAgentConfig processes agent.config events from the gateway. Updates
// agent metadata (channel) in the DB and broadcasts a fleet.update with the
// full fleet snapshot.
func (c *WSClient) handleAgentConfig(payload json.RawMessage) {
	c.logger.Debug("handleAgentConfig", "payload", string(payload))

	var cfg agentConfigPayload
	if err := json.Unmarshal(payload, &cfg); err != nil {
		c.logger.Warn("agent.config: unparseable payload, skipping", "error", err)
		return
	}

	if cfg.ID == "" {
		return
	}

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	update := models.UpdateAgentRequest{}

	if cfg.Channel != "" {
		update.Channel = &cfg.Channel
	}

	// DB update first
	updated, err := c.agents.Update(ctx, cfg.ID, update)
	if err != nil {
		c.logger.Warn("agent.config: DB update failed",
			"agentId", cfg.ID, "error", err)
		return
	}

	// Apply display name/role from config event
	if cfg.Name != "" {
		updated.DisplayName = cfg.Name
	}
	if cfg.Role != "" {
		updated.Role = cfg.Role
	}

	// Broadcast full fleet snapshot so frontend gets updated agent info
	allAgents, err := c.agents.List(ctx, "")
	if err != nil {
		c.logger.Warn("agent.config: fleet list failed, broadcasting single agent", "error", err)
		c.broker.Broadcast("agent.status", updated)
		return
	}

	c.broker.Broadcast("fleet.update", allAgents)

	c.logger.Debug("agent.config: fleet updated", "agentId", cfg.ID, "name", cfg.Name)
}