// Package db provides MySQL/TiDB connectivity and agent config queries.
package db

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"log"
	"strings"

	_ "github.com/go-sql-driver/mysql"
)

// AgentConfig holds the orchestrator/agent configuration loaded from DB.
type AgentConfig struct {
	ID           int
	Name         string
	Model        string
	SystemPrompt string
	AllowedTools []string
	Temperature  float64
	MaxTokens    int
	IsOrchestrator bool
	IsSystem     bool
	IsActive     bool
	// Container / Swarm fields (Phase A)
	ServiceName     string
	ServicePort     int
	ContainerImage  string
	ContainerStatus string // "stopped" | "deploying" | "running" | "error"
}

// AgentRow is a minimal agent representation for listing.
type AgentRow struct {
	ID          int    `json:"id"`
	Name        string `json:"name"`
	Role        string `json:"role"`
	Model       string `json:"model"`
	Description string `json:"description"`
	IsActive    bool   `json:"isActive"`
	IsSystem    bool   `json:"isSystem"`
	IsOrchestrator bool `json:"isOrchestrator"`
}

type DB struct {
	conn *sql.DB
}

func Connect(dsn string) (*DB, error) {
	if dsn == "" {
		return nil, fmt.Errorf("DATABASE_URL is empty")
	}
	// Convert mysql:// URL to DSN format if needed
	dsn = normalizeDSN(dsn)

	conn, err := sql.Open("mysql", dsn)
	if err != nil {
		return nil, fmt.Errorf("failed to open DB: %w", err)
	}
	if err := conn.Ping(); err != nil {
		return nil, fmt.Errorf("failed to ping DB: %w", err)
	}
	log.Println("[DB] Connected to MySQL")
	return &DB{conn: conn}, nil
}

func (d *DB) Close() {
	if d.conn != nil {
		_ = d.conn.Close()
	}
}

// GetOrchestratorConfig loads the agent with isOrchestrator=1 from DB.
func (d *DB) GetOrchestratorConfig() (*AgentConfig, error) {
	row := d.conn.QueryRow(`
		SELECT id, name, model, systemPrompt, allowedTools, temperature, maxTokens, isOrchestrator, isSystem, isActive,
		       COALESCE(serviceName,''), COALESCE(servicePort,0), COALESCE(containerImage,'goclaw-agent-worker:latest'), COALESCE(containerStatus,'stopped')
		FROM agents
		WHERE isOrchestrator = 1
		LIMIT 1
	`)
	return scanAgentConfig(row)
}

// GetAgentByID loads a specific agent by ID.
func (d *DB) GetAgentByID(id int) (*AgentConfig, error) {
	row := d.conn.QueryRow(`
		SELECT id, name, model, systemPrompt, allowedTools, temperature, maxTokens, isOrchestrator, isSystem, isActive,
		       COALESCE(serviceName,''), COALESCE(servicePort,0), COALESCE(containerImage,'goclaw-agent-worker:latest'), COALESCE(containerStatus,'stopped')
		FROM agents
		WHERE id = ?
		LIMIT 1
	`, id)
	return scanAgentConfig(row)
}

// ListAgents returns all active agents.
func (d *DB) ListAgents() ([]AgentRow, error) {
	rows, err := d.conn.Query(`
		SELECT id, name, role, model, COALESCE(description,''), isActive, isSystem, isOrchestrator
		FROM agents
		ORDER BY isOrchestrator DESC, isSystem DESC, id ASC
	`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var agents []AgentRow
	for rows.Next() {
		var a AgentRow
		var isActive, isSystem, isOrch int
		if err := rows.Scan(&a.ID, &a.Name, &a.Role, &a.Model, &a.Description, &isActive, &isSystem, &isOrch); err != nil {
			continue
		}
		a.IsActive = isActive == 1
		a.IsSystem = isSystem == 1
		a.IsOrchestrator = isOrch == 1
		agents = append(agents, a)
	}
	return agents, nil
}

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

func scanAgentConfig(row *sql.Row) (*AgentConfig, error) {
	var cfg AgentConfig
	var systemPrompt sql.NullString
	var allowedToolsJSON sql.NullString
	var temperature sql.NullFloat64
	var maxTokens sql.NullInt64
	var isOrch, isSystem, isActive int

	err := row.Scan(
		&cfg.ID, &cfg.Name, &cfg.Model,
		&systemPrompt, &allowedToolsJSON,
		&temperature, &maxTokens,
		&isOrch, &isSystem, &isActive,
		&cfg.ServiceName, &cfg.ServicePort, &cfg.ContainerImage, &cfg.ContainerStatus,
	)
	if err != nil {
		return nil, err
	}

	cfg.SystemPrompt = systemPrompt.String
	cfg.Temperature = temperature.Float64
	if cfg.Temperature == 0 {
		cfg.Temperature = 0.5
	}
	cfg.MaxTokens = int(maxTokens.Int64)
	if cfg.MaxTokens == 0 {
		cfg.MaxTokens = 8192
	}
	cfg.IsOrchestrator = isOrch == 1
	cfg.IsSystem = isSystem == 1
	cfg.IsActive = isActive == 1

	if allowedToolsJSON.Valid && allowedToolsJSON.String != "" && allowedToolsJSON.String != "null" {
		_ = json.Unmarshal([]byte(allowedToolsJSON.String), &cfg.AllowedTools)
	}

	return &cfg, nil
}

// ─── Agent Container Fields ───────────────────────────────────────────────────
// These methods support the agent-worker container architecture where each
// agent runs as an autonomous Docker Swarm service.

// UpdateContainerStatus updates the container lifecycle state of an agent.
func (d *DB) UpdateContainerStatus(agentID int, status, serviceName string, servicePort int) error {
	if d.conn == nil {
		return nil
	}
	_, err := d.conn.Exec(`
		UPDATE agents
		SET containerStatus = ?, serviceName = ?, servicePort = ?, updatedAt = NOW()
		WHERE id = ?
	`, status, serviceName, servicePort, agentID)
	return err
}

// HistoryInput holds data for one conversation entry.
type HistoryInput struct {
	AgentID        int
	UserMessage    string
	AgentResponse  string
	ConversationID string
	Status         string // "success" | "error" | "pending"
}

// HistoryRow is a single entry from agentHistory for sliding window memory.
type HistoryRow struct {
	ID            int    `json:"id"`
	UserMessage   string `json:"userMessage"`
	AgentResponse string `json:"agentResponse"`
	ConvID        string `json:"conversationId"`
}

// SaveHistory inserts a row into the agentHistory table.
// Non-fatal — logs on error but does not return one.
func (d *DB) SaveHistory(h HistoryInput) {
	if d.conn == nil {
		return
	}
	status := h.Status
	if status == "" {
		status = "success"
	}
	convID := sql.NullString{String: h.ConversationID, Valid: h.ConversationID != ""}
	resp := sql.NullString{String: h.AgentResponse, Valid: h.AgentResponse != ""}
	_, err := d.conn.Exec(`
		INSERT INTO agentHistory (agentId, userMessage, agentResponse, conversationId, status)
		VALUES (?, ?, ?, ?, ?)
	`,
		h.AgentID,
		truncate(h.UserMessage, 65535),
		resp,
		convID,
		status,
	)
	if err != nil {
		log.Printf("[DB] SaveHistory error: %v", err)
	}
}

// GetAgentHistory returns the last N conversation turns for an agent, oldest first.
func (d *DB) GetAgentHistory(agentID, limit int) ([]HistoryRow, error) {
	if d.conn == nil {
		return nil, nil
	}
	rows, err := d.conn.Query(`
		SELECT id, userMessage, COALESCE(agentResponse,''), COALESCE(conversationId,'')
		FROM agentHistory
		WHERE agentId = ?
		ORDER BY id DESC
		LIMIT ?
	`, agentID, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var result []HistoryRow
	for rows.Next() {
		var h HistoryRow
		if err := rows.Scan(&h.ID, &h.UserMessage, &h.AgentResponse, &h.ConvID); err != nil {
			continue
		}
		result = append(result, h)
	}
	// Reverse so oldest is first (for LLM context ordering)
	for i, j := 0, len(result)-1; i < j; i, j = i+1, j-1 {
		result[i], result[j] = result[j], result[i]
	}
	return result, nil
}

// truncate caps a string to maxLen bytes.
func truncate(s string, maxLen int) string {
	if len(s) <= maxLen {
		return s
	}
	return s[:maxLen]
}

// normalizeDSN converts mysql://user:pass@host:port/db to user:pass@tcp(host:port)/db
func normalizeDSN(dsn string) string {
	if !strings.HasPrefix(dsn, "mysql://") {
		return dsn
	}
	// Strip scheme
	dsn = strings.TrimPrefix(dsn, "mysql://")
	// user:pass@host:port/db → user:pass@tcp(host:port)/db
	atIdx := strings.LastIndex(dsn, "@")
	if atIdx < 0 {
		return dsn
	}
	userInfo := dsn[:atIdx]
	hostDB := dsn[atIdx+1:]

	// Split host:port/db
	slashIdx := strings.Index(hostDB, "/")
	var hostPort, dbName string
	if slashIdx >= 0 {
		hostPort = hostDB[:slashIdx]
		dbName = hostDB[slashIdx:]
	} else {
		hostPort = hostDB
		dbName = ""
	}

	// TiDB Cloud and other cloud MySQL require TLS — detect by host pattern
	tlsParam := ""
	if strings.Contains(hostPort, "tidbcloud") ||
		strings.Contains(hostPort, "tidb.cloud") ||
		strings.Contains(hostPort, "aws") ||
		strings.Contains(hostPort, "gcp") ||
		strings.Contains(hostPort, "azure") {
		tlsParam = "&tls=true"
	}
	// Also detect if the original DSN had ?ssl or ?tls params
	if strings.Contains(dbName, "ssl") || strings.Contains(dbName, "tls") {
		tlsParam = "" // already handled in dbName
	}
	return fmt.Sprintf("%s@tcp(%s)%s?parseTime=true&charset=utf8mb4%s", userInfo, hostPort, dbName, tlsParam)
}