package store

import (
	"context"
	"database/sql"
	"encoding/json"
	"strings"
	"time"
)

type Guild struct {
	ID             uint64
	Name           string
	OwnerID        uint64
	IconFileID     *uint64
	BannerFileID   *uint64
	SplashFileID   *uint64
	AccentColor    int64
	Description    string
	IsMain         bool
	IsDiscoverable bool
	Limits         map[string]int
	CreatedAt      time.Time
}

type GuildMember struct {
	GuildID      uint64
	UserID       uint64
	Nickname     string
	JoinedAt     time.Time
	TimeoutUntil *time.Time
}

// CreateGuildParams — параметры создания сервера. Роли по умолчанию создаёт
// вызывающий код (bootstrap или создатель сервера), чтобы можно было
// применить шаблон оформления (AGENT.md 7.3).
type CreateGuildParams struct {
	ID             uint64
	Name           string
	OwnerID        uint64
	IsMain         bool
	IsDiscoverable bool
	Description    string
	AccentColor    int64
	Limits         map[string]int
}

const guildColumns = `id, name, owner_id, icon_file_id, banner_file_id, splash_file_id,
	accent_color, description, is_main, is_discoverable, limits_json, created_at`

func (s *Store) CreateGuild(ctx context.Context, params CreateGuildParams) (*Guild, error) {
	if params.ID == 0 {
		params.ID = s.NextID()
	}
	limits := "{}"
	if len(params.Limits) > 0 {
		if encoded, err := json.Marshal(params.Limits); err == nil {
			limits = string(encoded)
		}
	}
	_, err := s.writer.ExecContext(ctx, `
		INSERT INTO guilds (id, name, owner_id, description, accent_color, is_main, is_discoverable, limits_json, created_at)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)`,
		int64(params.ID), params.Name, int64(params.OwnerID), params.Description, params.AccentColor,
		boolToInt(params.IsMain), boolToInt(params.IsDiscoverable), limits, s.Now())
	if err != nil {
		return nil, err
	}
	return s.GetGuild(ctx, params.ID)
}

func (s *Store) GetGuild(ctx context.Context, id uint64) (*Guild, error) {
	return scanGuild(s.reader.QueryRowContext(ctx, `SELECT `+guildColumns+` FROM guilds WHERE id = ?`, int64(id)))
}

func (s *Store) GetMainGuild(ctx context.Context) (*Guild, error) {
	return scanGuild(s.reader.QueryRowContext(ctx,
		`SELECT `+guildColumns+` FROM guilds WHERE is_main = 1 ORDER BY id LIMIT 1`))
}

type UpdateGuildParams struct {
	Name           *string
	Description    *string
	AccentColor    *int64
	IconFileID     *uint64
	BannerFileID   *uint64
	SplashFileID   *uint64
	IsDiscoverable *bool
	Limits         map[string]int
}

func (s *Store) UpdateGuild(ctx context.Context, id uint64, params UpdateGuildParams) (*Guild, error) {
	var (
		sets []string
		args []any
	)
	if params.Name != nil {
		sets = append(sets, "name = ?")
		args = append(args, *params.Name)
	}
	if params.Description != nil {
		sets = append(sets, "description = ?")
		args = append(args, *params.Description)
	}
	if params.AccentColor != nil {
		sets = append(sets, "accent_color = ?")
		args = append(args, *params.AccentColor)
	}
	if params.IconFileID != nil {
		sets = append(sets, "icon_file_id = ?")
		args = append(args, int64(*params.IconFileID))
	}
	if params.BannerFileID != nil {
		sets = append(sets, "banner_file_id = ?")
		args = append(args, int64(*params.BannerFileID))
	}
	if params.SplashFileID != nil {
		sets = append(sets, "splash_file_id = ?")
		args = append(args, int64(*params.SplashFileID))
	}
	if params.IsDiscoverable != nil {
		sets = append(sets, "is_discoverable = ?")
		args = append(args, boolToInt(*params.IsDiscoverable))
	}
	if params.Limits != nil {
		encoded, err := json.Marshal(params.Limits)
		if err != nil {
			return nil, err
		}
		sets = append(sets, "limits_json = ?")
		args = append(args, string(encoded))
	}
	if len(sets) == 0 {
		return s.GetGuild(ctx, id)
	}
	args = append(args, int64(id))
	result, err := s.writer.ExecContext(ctx, buildQuery(updateGuildTemplate, joinSets(sets)), args...)
	if err != nil {
		return nil, err
	}
	if affected, err := result.RowsAffected(); err == nil && affected == 0 {
		return nil, ErrNotFound
	}
	return s.GetGuild(ctx, id)
}

func (s *Store) DeleteGuild(ctx context.Context, id uint64) error {
	_, err := s.writer.ExecContext(ctx, `DELETE FROM guilds WHERE id = ?`, int64(id))
	return err
}

// ListGuildsForUser возвращает серверы пользователя (участие).
func (s *Store) ListGuildsForUser(ctx context.Context, userID uint64) ([]Guild, error) {
	rows, err := s.reader.QueryContext(ctx, buildQuery(selectGuildsForUserTemplate, prefixColumns("g", guildColumns)), int64(userID))
	if err != nil {
		return nil, err
	}
	return collectGuilds(rows)
}

// ListAllGuilds используется инстанс-админом (AGENT.md 7.19).
func (s *Store) ListAllGuilds(ctx context.Context) ([]Guild, error) {
	rows, err := s.reader.QueryContext(ctx, `SELECT `+guildColumns+` FROM guilds ORDER BY id`)
	if err != nil {
		return nil, err
	}
	return collectGuilds(rows)
}

func (s *Store) CountGuildsForUser(ctx context.Context, userID uint64) (int, error) {
	var count int
	err := s.reader.QueryRowContext(ctx, `SELECT COUNT(*) FROM guild_members WHERE user_id = ?`, int64(userID)).Scan(&count)
	return count, err
}

func (s *Store) CountGuildMembers(ctx context.Context, guildID uint64) (int, error) {
	var count int
	err := s.reader.QueryRowContext(ctx, `SELECT COUNT(*) FROM guild_members WHERE guild_id = ?`, int64(guildID)).Scan(&count)
	return count, err
}

func (s *Store) AddGuildMember(ctx context.Context, guildID, userID uint64, nickname string) (*GuildMember, error) {
	_, err := s.writer.ExecContext(ctx, `
		INSERT INTO guild_members (guild_id, user_id, nickname, joined_at) VALUES (?, ?, ?, ?)
		ON CONFLICT (guild_id, user_id) DO NOTHING`,
		int64(guildID), int64(userID), nullableString(nickname), s.Now())
	if err != nil {
		return nil, err
	}
	return s.GetGuildMember(ctx, guildID, userID)
}

func (s *Store) GetGuildMember(ctx context.Context, guildID, userID uint64) (*GuildMember, error) {
	var (
		member       GuildMember
		nickname     sql.NullString
		joinedAt     string
		timeoutUntil sql.NullString
	)
	err := s.reader.QueryRowContext(ctx, `
		SELECT guild_id, user_id, nickname, joined_at, timeout_until
		FROM guild_members WHERE guild_id = ? AND user_id = ?`, int64(guildID), int64(userID)).
		Scan(&member.GuildID, &member.UserID, &nickname, &joinedAt, &timeoutUntil)
	if err != nil {
		return nil, mapError(err)
	}
	if nickname.Valid {
		member.Nickname = nickname.String
	}
	member.JoinedAt = parseTimestamp(joinedAt)
	if timeoutUntil.Valid {
		value := parseTimestamp(timeoutUntil.String)
		member.TimeoutUntil = &value
	}
	return &member, nil
}

func (s *Store) ListGuildMembers(ctx context.Context, guildID uint64) ([]GuildMember, error) {
	rows, err := s.reader.QueryContext(ctx, `
		SELECT guild_id, user_id, nickname, joined_at, timeout_until
		FROM guild_members WHERE guild_id = ? ORDER BY joined_at`, int64(guildID))
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	members := make([]GuildMember, 0, 16)
	for rows.Next() {
		var (
			member       GuildMember
			nickname     sql.NullString
			joinedAt     string
			timeoutUntil sql.NullString
		)
		if err := rows.Scan(&member.GuildID, &member.UserID, &nickname, &joinedAt, &timeoutUntil); err != nil {
			return nil, err
		}
		if nickname.Valid {
			member.Nickname = nickname.String
		}
		member.JoinedAt = parseTimestamp(joinedAt)
		if timeoutUntil.Valid {
			value := parseTimestamp(timeoutUntil.String)
			member.TimeoutUntil = &value
		}
		members = append(members, member)
	}
	return members, rows.Err()
}

func (s *Store) UpdateGuildMember(ctx context.Context, guildID, userID uint64, nickname *string, timeoutUntil *time.Time) error {
	sets := []string{}
	args := []any{}
	if nickname != nil {
		sets = append(sets, "nickname = ?")
		args = append(args, nullableString(*nickname))
	}
	if timeoutUntil != nil {
		if timeoutUntil.IsZero() {
			sets = append(sets, "timeout_until = NULL")
		} else {
			sets = append(sets, "timeout_until = ?")
			args = append(args, s.Timestamp(*timeoutUntil))
		}
	}
	if len(sets) == 0 {
		return nil
	}
	args = append(args, int64(guildID), int64(userID))
	_, err := s.writer.ExecContext(ctx, buildQuery(updateGuildMemberTemplate, joinSets(sets)), args...)
	return err
}

// TimeoutFromNow возвращает момент окончания тайм-аута (AGENT.md 7.10).
func TimeoutFromNow(days int) time.Time {
	if days < 1 {
		days = 1
	}
	return time.Now().UTC().AddDate(0, 0, days)
}

func (s *Store) RemoveGuildMember(ctx context.Context, guildID, userID uint64) error {
	_, err := s.writer.ExecContext(ctx, `DELETE FROM guild_members WHERE guild_id = ? AND user_id = ?`,
		int64(guildID), int64(userID))
	return err
}

func (s *Store) TransferGuildOwnership(ctx context.Context, guildID, newOwnerID uint64) error {
	result, err := s.writer.ExecContext(ctx, `UPDATE guilds SET owner_id = ? WHERE id = ?`,
		int64(newOwnerID), int64(guildID))
	if err != nil {
		return err
	}
	if affected, err := result.RowsAffected(); err == nil && affected == 0 {
		return ErrNotFound
	}
	return nil
}

func scanGuild(scanner interface{ Scan(...any) error }) (*Guild, error) {
	var (
		guild      Guild
		iconID     sql.NullInt64
		bannerID   sql.NullInt64
		splashID   sql.NullInt64
		isMain     int
		discover   int
		limitsJSON string
		createdAt  string
	)
	err := scanner.Scan(&guild.ID, &guild.Name, &guild.OwnerID, &iconID, &bannerID, &splashID,
		&guild.AccentColor, &guild.Description, &isMain, &discover, &limitsJSON, &createdAt)
	if err != nil {
		return nil, mapError(err)
	}
	guild.IconFileID = optionalID(iconID)
	guild.BannerFileID = optionalID(bannerID)
	guild.SplashFileID = optionalID(splashID)
	guild.IsMain = isMain == 1
	guild.IsDiscoverable = discover == 1
	if limitsJSON != "" && limitsJSON != "{}" {
		_ = json.Unmarshal([]byte(limitsJSON), &guild.Limits)
	}
	guild.CreatedAt = parseTimestamp(createdAt)
	return &guild, nil
}

func collectGuilds(rows *sql.Rows) ([]Guild, error) {
	defer rows.Close()
	guilds := make([]Guild, 0, 8)
	for rows.Next() {
		guild, err := scanGuild(rows)
		if err != nil {
			return nil, err
		}
		guilds = append(guilds, *guild)
	}
	return guilds, rows.Err()
}

func nullableString(value string) any {
	if value == "" {
		return nil
	}
	return value
}

func joinSets(sets []string) string {
	return strings.Join(sets, ", ")
}

// prefixColumns добавляет префикс таблицы к списку колонок.
func prefixColumns(prefix, columns string) string {
	parts := strings.Split(columns, ",")
	for i, part := range parts {
		parts[i] = prefix + "." + strings.TrimSpace(part)
	}
	return strings.Join(parts, ", ")
}