package db

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

	"git.wntrmute.dev/mc/mcias/internal/model"
)

const ssoClientCols = `id, client_id, redirect_uri, tags_json, enabled, created_by, created_at, updated_at`

// CreateSSOClient inserts a new SSO client. The client_id must be unique
// and the redirect_uri must start with "https://".
func (db *DB) CreateSSOClient(clientID, redirectURI string, tags []string, createdBy *int64) (*model.SSOClient, error) {
	if clientID == "" {
		return nil, fmt.Errorf("db: client_id is required")
	}
	if !strings.HasPrefix(redirectURI, "https://") {
		return nil, fmt.Errorf("db: redirect_uri must start with https://")
	}
	if tags == nil {
		tags = []string{}
	}

	tagsJSON, err := json.Marshal(tags)
	if err != nil {
		return nil, fmt.Errorf("db: marshal tags: %w", err)
	}

	n := now()
	result, err := db.sql.Exec(`
		INSERT INTO sso_clients (client_id, redirect_uri, tags_json, enabled, created_by, created_at, updated_at)
		VALUES (?, ?, ?, 1, ?, ?, ?)
	`, clientID, redirectURI, string(tagsJSON), createdBy, n, n)
	if err != nil {
		return nil, fmt.Errorf("db: create SSO client: %w", err)
	}

	id, err := result.LastInsertId()
	if err != nil {
		return nil, fmt.Errorf("db: create SSO client last insert id: %w", err)
	}

	createdAt, err := parseTime(n)
	if err != nil {
		return nil, err
	}

	return &model.SSOClient{
		ID:          id,
		ClientID:    clientID,
		RedirectURI: redirectURI,
		Tags:        tags,
		Enabled:     true,
		CreatedBy:   createdBy,
		CreatedAt:   createdAt,
		UpdatedAt:   createdAt,
	}, nil
}

// GetSSOClient retrieves an SSO client by client_id.
// Returns ErrNotFound if no such client exists.
func (db *DB) GetSSOClient(clientID string) (*model.SSOClient, error) {
	return scanSSOClient(db.sql.QueryRow(`
		SELECT `+ssoClientCols+`
		FROM sso_clients WHERE client_id = ?
	`, clientID))
}

// ListSSOClients returns all SSO clients ordered by client_id.
func (db *DB) ListSSOClients() ([]*model.SSOClient, error) {
	rows, err := db.sql.Query(`
		SELECT ` + ssoClientCols + `
		FROM sso_clients ORDER BY client_id ASC
	`)
	if err != nil {
		return nil, fmt.Errorf("db: list SSO clients: %w", err)
	}
	defer func() { _ = rows.Close() }()

	var clients []*model.SSOClient
	for rows.Next() {
		c, err := scanSSOClientRow(rows)
		if err != nil {
			return nil, err
		}
		clients = append(clients, c)
	}
	return clients, rows.Err()
}

// UpdateSSOClient updates the mutable fields of an SSO client.
// Only non-nil fields are changed.
func (db *DB) UpdateSSOClient(clientID string, redirectURI *string, tags *[]string, enabled *bool) error {
	n := now()
	setClauses := "updated_at = ?"
	args := []interface{}{n}

	if redirectURI != nil {
		if !strings.HasPrefix(*redirectURI, "https://") {
			return fmt.Errorf("db: redirect_uri must start with https://")
		}
		setClauses += ", redirect_uri = ?"
		args = append(args, *redirectURI)
	}
	if tags != nil {
		tagsJSON, err := json.Marshal(*tags)
		if err != nil {
			return fmt.Errorf("db: marshal tags: %w", err)
		}
		setClauses += ", tags_json = ?"
		args = append(args, string(tagsJSON))
	}
	if enabled != nil {
		enabledInt := 0
		if *enabled {
			enabledInt = 1
		}
		setClauses += ", enabled = ?"
		args = append(args, enabledInt)
	}
	args = append(args, clientID)

	res, err := db.sql.Exec(`UPDATE sso_clients SET `+setClauses+` WHERE client_id = ?`, args...)
	if err != nil {
		return fmt.Errorf("db: update SSO client %s: %w", clientID, err)
	}
	n2, _ := res.RowsAffected()
	if n2 == 0 {
		return ErrNotFound
	}
	return nil
}

// DeleteSSOClient removes an SSO client by client_id.
func (db *DB) DeleteSSOClient(clientID string) error {
	res, err := db.sql.Exec(`DELETE FROM sso_clients WHERE client_id = ?`, clientID)
	if err != nil {
		return fmt.Errorf("db: delete SSO client %s: %w", clientID, err)
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return ErrNotFound
	}
	return nil
}

// scanSSOClient scans a single SSO client from a *sql.Row.
func scanSSOClient(row *sql.Row) (*model.SSOClient, error) {
	var c model.SSOClient
	var enabledInt int
	var tagsJSON, createdAtStr, updatedAtStr string
	var createdBy *int64

	err := row.Scan(&c.ID, &c.ClientID, &c.RedirectURI, &tagsJSON,
		&enabledInt, &createdBy, &createdAtStr, &updatedAtStr)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("db: scan SSO client: %w", err)
	}

	return finishSSOClientScan(&c, enabledInt, createdBy, tagsJSON, createdAtStr, updatedAtStr)
}

// scanSSOClientRow scans a single SSO client from *sql.Rows.
func scanSSOClientRow(rows *sql.Rows) (*model.SSOClient, error) {
	var c model.SSOClient
	var enabledInt int
	var tagsJSON, createdAtStr, updatedAtStr string
	var createdBy *int64

	err := rows.Scan(&c.ID, &c.ClientID, &c.RedirectURI, &tagsJSON,
		&enabledInt, &createdBy, &createdAtStr, &updatedAtStr)
	if err != nil {
		return nil, fmt.Errorf("db: scan SSO client row: %w", err)
	}

	return finishSSOClientScan(&c, enabledInt, createdBy, tagsJSON, createdAtStr, updatedAtStr)
}

func finishSSOClientScan(c *model.SSOClient, enabledInt int, createdBy *int64, tagsJSON, createdAtStr, updatedAtStr string) (*model.SSOClient, error) {
	c.Enabled = enabledInt == 1
	c.CreatedBy = createdBy

	var err error
	if c.CreatedAt, err = parseTime(createdAtStr); err != nil {
		return nil, err
	}
	if c.UpdatedAt, err = parseTime(updatedAtStr); err != nil {
		return nil, err
	}

	if err := json.Unmarshal([]byte(tagsJSON), &c.Tags); err != nil {
		return nil, fmt.Errorf("db: unmarshal SSO client tags: %w", err)
	}
	if c.Tags == nil {
		c.Tags = []string{}
	}

	return c, nil
}