package handlers

import (
	"encoding/json"
	"math"
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
	"golang.org/x/crypto/bcrypt"

	"git.gobha.me/xcaliber/chat-switchboard/database"
	"git.gobha.me/xcaliber/chat-switchboard/providers"
)

// ── Types ───────────────────────────────────

type adminUserResponse struct {
	ID          string  `json:"id"`
	Username    string  `json:"username"`
	Email       string  `json:"email"`
	DisplayName *string `json:"display_name"`
	Role        string  `json:"role"`
	IsActive    bool    `json:"is_active"`
	CreatedAt   string  `json:"created_at"`
	UpdatedAt   string  `json:"updated_at"`
	LastLoginAt *string `json:"last_login_at"`
}

type adminCreateUserRequest struct {
	Username string `json:"username" binding:"required,min=3,max=50"`
	Email    string `json:"email"    binding:"required,email"`
	Password string `json:"password" binding:"required,min=8,max=128"`
	Role     string `json:"role"     binding:"required,oneof=user admin moderator"`
}

type adminResetPasswordRequest struct {
	NewPassword string `json:"new_password" binding:"required,min=8,max=128"`
}

type updateUserRoleRequest struct {
	Role string `json:"role" binding:"required,oneof=user admin moderator"`
}

type updateUserActiveRequest struct {
	IsActive bool `json:"is_active"`
}

type globalSettingResponse struct {
	Key       string                 `json:"key"`
	Value     map[string]interface{} `json:"value"`
	UpdatedAt string                 `json:"updated_at"`
}

// AdminHandler manages admin-only operations.
type AdminHandler struct{}

// NewAdminHandler creates a new handler.
func NewAdminHandler() *AdminHandler {
	return &AdminHandler{}
}

// ── List Users ──────────────────────────────

func (h *AdminHandler) ListUsers(c *gin.Context) {
	page, perPage, offset := parsePagination(c)

	var total int
	if err := database.DB.QueryRow(`SELECT COUNT(*) FROM users`).Scan(&total); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to count users"})
		return
	}

	rows, err := database.DB.Query(`
		SELECT id, username, email, display_name, role, is_active,
		       created_at, updated_at, last_login_at
		FROM users
		ORDER BY created_at ASC
		LIMIT $1 OFFSET $2
	`, perPage, offset)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to list users"})
		return
	}
	defer rows.Close()

	users := make([]adminUserResponse, 0)
	for rows.Next() {
		var u adminUserResponse
		if err := rows.Scan(
			&u.ID, &u.Username, &u.Email, &u.DisplayName, &u.Role,
			&u.IsActive, &u.CreatedAt, &u.UpdatedAt, &u.LastLoginAt,
		); err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to scan user"})
			return
		}
		users = append(users, u)
	}

	c.JSON(http.StatusOK, paginatedResponse{
		Data:       users,
		Page:       page,
		PerPage:    perPage,
		Total:      total,
		TotalPages: int(math.Ceil(float64(total) / float64(perPage))),
	})
}

// ── Create User (admin) ─────────────────────

func (h *AdminHandler) CreateUser(c *gin.Context) {
	var req adminCreateUserRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	req.Email = strings.ToLower(strings.TrimSpace(req.Email))
	req.Username = strings.TrimSpace(req.Username)

	hash, err := bcrypt.GenerateFromPassword([]byte(req.Password), bcryptCost)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to hash password"})
		return
	}

	var user adminUserResponse
	err = database.DB.QueryRow(`
		INSERT INTO users (username, email, password_hash, role)
		VALUES ($1, $2, $3, $4)
		RETURNING id, username, email, display_name, role, is_active, created_at, updated_at, last_login_at
	`, req.Username, req.Email, string(hash), req.Role).Scan(
		&user.ID, &user.Username, &user.Email, &user.DisplayName,
		&user.Role, &user.IsActive, &user.CreatedAt, &user.UpdatedAt, &user.LastLoginAt,
	)
	if err != nil {
		if strings.Contains(err.Error(), "duplicate key") {
			field := "email"
			if strings.Contains(err.Error(), "username") {
				field = "username"
			}
			c.JSON(http.StatusConflict, gin.H{"error": field + " already taken"})
			return
		}
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to create user"})
		return
	}

	c.JSON(http.StatusCreated, user)
}

// ── Reset Password (admin) ──────────────────

func (h *AdminHandler) ResetPassword(c *gin.Context) {
	targetID := c.Param("id")

	var req adminResetPasswordRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	hash, err := bcrypt.GenerateFromPassword([]byte(req.NewPassword), bcryptCost)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to hash password"})
		return
	}

	result, err := database.DB.Exec(
		`UPDATE users SET password_hash = $1, updated_at = NOW() WHERE id = $2`,
		string(hash), targetID,
	)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to reset password"})
		return
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		c.JSON(http.StatusNotFound, gin.H{"error": "user not found"})
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": "password reset"})
}

// ── Update User Role ────────────────────────

func (h *AdminHandler) UpdateUserRole(c *gin.Context) {
	targetID := c.Param("id")
	adminID := getUserID(c)

	var req updateUserRoleRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// Prevent admin from demoting themselves
	if targetID == adminID && req.Role != "admin" {
		c.JSON(http.StatusForbidden, gin.H{"error": "cannot change your own role"})
		return
	}

	result, err := database.DB.Exec(
		`UPDATE users SET role = $1, updated_at = NOW() WHERE id = $2`,
		req.Role, targetID,
	)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to update role"})
		return
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		c.JSON(http.StatusNotFound, gin.H{"error": "user not found"})
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": "role updated", "role": req.Role})
}

// ── Toggle User Active ──────────────────────

func (h *AdminHandler) ToggleUserActive(c *gin.Context) {
	targetID := c.Param("id")
	adminID := getUserID(c)

	var req updateUserActiveRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// Prevent admin from deactivating themselves
	if targetID == adminID && !req.IsActive {
		c.JSON(http.StatusForbidden, gin.H{"error": "cannot deactivate your own account"})
		return
	}

	result, err := database.DB.Exec(
		`UPDATE users SET is_active = $1, updated_at = NOW() WHERE id = $2`,
		req.IsActive, targetID,
	)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to update user"})
		return
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		c.JSON(http.StatusNotFound, gin.H{"error": "user not found"})
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": "user updated", "is_active": req.IsActive})
}

// ── Delete User ─────────────────────────────

func (h *AdminHandler) DeleteUser(c *gin.Context) {
	targetID := c.Param("id")
	adminID := getUserID(c)

	if targetID == adminID {
		c.JSON(http.StatusForbidden, gin.H{"error": "cannot delete your own account"})
		return
	}

	result, err := database.DB.Exec(`DELETE FROM users WHERE id = $1`, targetID)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to delete user"})
		return
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		c.JSON(http.StatusNotFound, gin.H{"error": "user not found"})
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": "user deleted"})
}

// ── Public Settings (for any authenticated user) ──

var publicSettingKeys = map[string]bool{
	"banner":                     true,
	"user_providers_enabled":     true,
	"registration_enabled":       true,
	"registration_default_state": true,
	"banner_presets":             true,
}

func (h *AdminHandler) PublicSettings(c *gin.Context) {
	rows, err := database.DB.Query(`
		SELECT key, value::text FROM global_settings ORDER BY key
	`)
	if err != nil {
		c.JSON(http.StatusOK, gin.H{"settings": []interface{}{}})
		return
	}
	defer rows.Close()

	settings := make([]globalSettingResponse, 0)
	for rows.Next() {
		var key, valueRaw string
		if err := rows.Scan(&key, &valueRaw); err != nil {
			continue
		}
		if !publicSettingKeys[key] {
			continue
		}
		s := globalSettingResponse{Key: key}
		s.Value = make(map[string]interface{})
		_ = json.Unmarshal([]byte(valueRaw), &s.Value)
		settings = append(settings, s)
	}

	c.JSON(http.StatusOK, gin.H{"settings": settings})
}

// ── List Global Settings ────────────────────

func (h *AdminHandler) ListGlobalSettings(c *gin.Context) {
	rows, err := database.DB.Query(`
		SELECT key, value::text, updated_at FROM global_settings ORDER BY key
	`)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to list settings"})
		return
	}
	defer rows.Close()

	settings := make([]globalSettingResponse, 0)
	for rows.Next() {
		var s globalSettingResponse
		var valueRaw string
		if err := rows.Scan(&s.Key, &valueRaw, &s.UpdatedAt); err != nil {
			continue
		}
		s.Value = make(map[string]interface{})
		_ = json.Unmarshal([]byte(valueRaw), &s.Value)
		settings = append(settings, s)
	}

	c.JSON(http.StatusOK, gin.H{"settings": settings})
}

// ── Get Global Setting ──────────────────────

func (h *AdminHandler) GetGlobalSetting(c *gin.Context) {
	key := c.Param("key")

	var valueRaw, updatedAt string
	err := database.DB.QueryRow(`
		SELECT value::text, updated_at FROM global_settings WHERE key = $1
	`, key).Scan(&valueRaw, &updatedAt)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "setting not found"})
		return
	}

	value := make(map[string]interface{})
	_ = json.Unmarshal([]byte(valueRaw), &value)

	c.JSON(http.StatusOK, globalSettingResponse{
		Key:       key,
		Value:     value,
		UpdatedAt: updatedAt,
	})
}

// ── Update Global Setting ───────────────────

func (h *AdminHandler) UpdateGlobalSetting(c *gin.Context) {
	key := c.Param("key")
	adminID := getUserID(c)

	var value map[string]interface{}
	if err := c.ShouldBindJSON(&value); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	valueJSON, err := json.Marshal(value)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid value"})
		return
	}

	_, err = database.DB.Exec(`
		INSERT INTO global_settings (key, value, updated_at, updated_by)
		VALUES ($1, $2::jsonb, NOW(), $3)
		ON CONFLICT (key) DO UPDATE SET
			value = $2::jsonb, updated_at = NOW(), updated_by = $3
	`, key, string(valueJSON), adminID)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to update setting"})
		return
	}

	h.GetGlobalSetting(c)
}

// ── Admin Stats ─────────────────────────────

func (h *AdminHandler) GetStats(c *gin.Context) {
	stats := make(map[string]int)

	queries := map[string]string{
		"total_users":    "SELECT COUNT(*) FROM users",
		"active_users":   "SELECT COUNT(*) FROM users WHERE is_active = true",
		"total_channels":  "SELECT COUNT(*) FROM channels",
		"total_messages": "SELECT COUNT(*) FROM messages",
		"api_configs":    "SELECT COUNT(*) FROM api_configs",
	}

	for key, query := range queries {
		var count int
		if err := database.DB.QueryRow(query).Scan(&count); err != nil {
			stats[key] = 0
		} else {
			stats[key] = count
		}
	}

	c.JSON(http.StatusOK, stats)
}

// ── Global API Configs ──────────────────────

type adminGlobalConfigResponse struct {
	ID           string  `json:"id"`
	Name         string  `json:"name"`
	Provider     string  `json:"provider"`
	Endpoint     string  `json:"endpoint"`
	ModelDefault *string `json:"model_default"`
	IsActive     bool    `json:"is_active"`
	HasKey       bool    `json:"has_key"`
	CreatedAt    string  `json:"created_at"`
}

func (h *AdminHandler) ListGlobalConfigs(c *gin.Context) {
	rows, err := database.DB.Query(`
		SELECT id, name, provider, endpoint, model_default, is_active,
		       (api_key_encrypted IS NOT NULL AND api_key_encrypted != '') as has_key,
		       created_at
		FROM api_configs
		WHERE user_id IS NULL
		ORDER BY created_at ASC
	`)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to list configs"})
		return
	}
	defer rows.Close()

	configs := make([]adminGlobalConfigResponse, 0)
	for rows.Next() {
		var cfg adminGlobalConfigResponse
		if err := rows.Scan(
			&cfg.ID, &cfg.Name, &cfg.Provider, &cfg.Endpoint,
			&cfg.ModelDefault, &cfg.IsActive, &cfg.HasKey, &cfg.CreatedAt,
		); err != nil {
			continue
		}
		configs = append(configs, cfg)
	}

	c.JSON(http.StatusOK, gin.H{"configs": configs})
}

func (h *AdminHandler) CreateGlobalConfig(c *gin.Context) {
	var req createAPIConfigRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	var id string
	err := database.DB.QueryRow(`
		INSERT INTO api_configs (name, provider, endpoint, api_key_encrypted, model_default, user_id, is_global)
		VALUES ($1, $2, $3, $4, $5, NULL, true)
		RETURNING id
	`, req.Name, req.Provider, req.Endpoint, req.APIKey, req.ModelDefault).Scan(&id)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to create config"})
		return
	}

	c.JSON(http.StatusCreated, gin.H{"id": id, "message": "global config created"})
}

func (h *AdminHandler) DeleteGlobalConfig(c *gin.Context) {
	configID := c.Param("id")

	result, err := database.DB.Exec(
		`DELETE FROM api_configs WHERE id = $1 AND user_id IS NULL`,
		configID,
	)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to delete config"})
		return
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		c.JSON(http.StatusNotFound, gin.H{"error": "global config not found"})
		return
	}

	c.JSON(http.StatusOK, gin.H{"message": "global config deleted"})
}

// ── Model Configs ───────────────────────────

type modelConfigResponse struct {
	ID           string                 `json:"id"`
	APIConfigID  string                 `json:"api_config_id"`
	ProviderName string                 `json:"provider_name"`
	ModelID      string                 `json:"model_id"`
	DisplayName  *string                `json:"display_name"`
	IsEnabled    bool                   `json:"is_enabled"`
	Capabilities map[string]interface{} `json:"capabilities"`
	CreatedAt    string                 `json:"created_at"`
	UpdatedAt    string                 `json:"updated_at"`
}

type updateModelConfigRequest struct {
	IsEnabled    *bool                  `json:"is_enabled"`
	DisplayName  *string                `json:"display_name"`
	Capabilities map[string]interface{} `json:"capabilities"`
}

func (h *AdminHandler) ListModelConfigs(c *gin.Context) {
	rows, err := database.DB.Query(`
		SELECT mc.id, mc.api_config_id, ac.name, mc.model_id, mc.display_name,
		       mc.is_enabled, mc.capabilities, mc.created_at, mc.updated_at
		FROM model_configs mc
		JOIN api_configs ac ON mc.api_config_id = ac.id
		WHERE ac.user_id IS NULL
		ORDER BY ac.name, mc.model_id
	`)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to list models"})
		return
	}
	defer rows.Close()

	models := make([]modelConfigResponse, 0)
	for rows.Next() {
		var m modelConfigResponse
		var capsJSON []byte
		if err := rows.Scan(
			&m.ID, &m.APIConfigID, &m.ProviderName, &m.ModelID, &m.DisplayName,
			&m.IsEnabled, &capsJSON, &m.CreatedAt, &m.UpdatedAt,
		); err != nil {
			continue
		}
		_ = json.Unmarshal(capsJSON, &m.Capabilities)
		models = append(models, m)
	}

	c.JSON(http.StatusOK, gin.H{"models": models})
}

func (h *AdminHandler) FetchModels(c *gin.Context) {
	// Load all global api_configs
	rows, err := database.DB.Query(`
		SELECT id, provider, endpoint, api_key_encrypted, custom_headers
		FROM api_configs
		WHERE user_id IS NULL AND is_active = true
	`)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to list configs"})
		return
	}
	defer rows.Close()

	type fetchResult struct {
		ConfigID string `json:"config_id"`
		Provider string `json:"provider"`
		Added    int    `json:"added"`
		Updated  int    `json:"updated"`
		Skipped  int    `json:"skipped"`
		Error    string `json:"error,omitempty"`
	}
	results := make([]fetchResult, 0)
	totalAdded := 0

	for rows.Next() {
		var cfgID, providerID, endpoint string
		var apiKey *string
		var customHeadersJSON []byte
		if err := rows.Scan(&cfgID, &providerID, &endpoint, &apiKey, &customHeadersJSON); err != nil {
			continue
		}

		prov, err := providers.Get(providerID)
		if err != nil {
			results = append(results, fetchResult{ConfigID: cfgID, Provider: providerID, Error: err.Error()})
			continue
		}

		key := ""
		if apiKey != nil {
			key = *apiKey
		}

		customHeaders := make(map[string]string)
		if customHeadersJSON != nil {
			_ = json.Unmarshal(customHeadersJSON, &customHeaders)
		}

		models, err := prov.ListModels(c.Request.Context(), providers.ProviderConfig{
			Endpoint:      endpoint,
			APIKey:        key,
			CustomHeaders: customHeaders,
		})
		if err != nil {
			results = append(results, fetchResult{ConfigID: cfgID, Provider: providerID, Error: err.Error()})
			continue
		}

		fr := fetchResult{ConfigID: cfgID, Provider: providerID}
		for _, m := range models {
			// Serialize capabilities to JSONB
			capsJSON, _ := json.Marshal(m.Capabilities)

			result, err := database.DB.Exec(`
				INSERT INTO model_configs (api_config_id, model_id, display_name, capabilities)
				VALUES ($1, $2, $3, $4)
				ON CONFLICT (api_config_id, model_id)
				DO UPDATE SET
					display_name = COALESCE(NULLIF(model_configs.display_name, ''), EXCLUDED.display_name),
					capabilities = EXCLUDED.capabilities,
					updated_at = NOW()
			`, cfgID, m.ID, m.Name, capsJSON)
			if err != nil {
				fr.Skipped++
				continue
			}
			affected, _ := result.RowsAffected()
			if affected > 0 {
				fr.Added++
				totalAdded++
			} else {
				fr.Skipped++
			}
		}
		results = append(results, fr)
	}

	c.JSON(http.StatusOK, gin.H{
		"total_added": totalAdded,
		"results":     results,
	})
}

func (h *AdminHandler) UpdateModelConfig(c *gin.Context) {
	modelID := c.Param("id")

	var req updateModelConfigRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// Build dynamic update
	if req.IsEnabled != nil {
		_, err := database.DB.Exec(
			`UPDATE model_configs SET is_enabled = $1, updated_at = NOW() WHERE id = $2`,
			*req.IsEnabled, modelID,
		)
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to update enabled"})
			return
		}
	}

	if req.DisplayName != nil {
		_, err := database.DB.Exec(
			`UPDATE model_configs SET display_name = $1, updated_at = NOW() WHERE id = $2`,
			*req.DisplayName, modelID,
		)
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to update name"})
			return
		}
	}

	if req.Capabilities != nil {
		capsJSON, err := json.Marshal(req.Capabilities)
		if err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": "invalid capabilities"})
			return
		}
		_, err = database.DB.Exec(
			`UPDATE model_configs SET capabilities = $1, updated_at = NOW() WHERE id = $2`,
			string(capsJSON), modelID,
		)
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to update capabilities"})
			return
		}
	}

	c.JSON(http.StatusOK, gin.H{"message": "model updated"})
}

// BulkUpdateModels enables or disables all models at once
func (h *AdminHandler) BulkUpdateModels(c *gin.Context) {
	var req struct {
		IsEnabled bool `json:"is_enabled"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	result, err := database.DB.Exec(
		`UPDATE model_configs SET is_enabled = $1, updated_at = NOW()`,
		req.IsEnabled,
	)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to bulk update models"})
		return
	}
	rows, _ := result.RowsAffected()
	c.JSON(http.StatusOK, gin.H{"message": "models updated", "count": rows})
}

func (h *AdminHandler) DeleteModelConfig(c *gin.Context) {
	modelID := c.Param("id")
	result, err := database.DB.Exec(`DELETE FROM model_configs WHERE id = $1`, modelID)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to delete model"})
		return
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		c.JSON(http.StatusNotFound, gin.H{"error": "model not found"})
		return
	}
	c.JSON(http.StatusOK, gin.H{"message": "model deleted"})
}