package postgres

import (
	"context"
	"database/sql"
	"fmt"

	"git.gobha.me/xcaliber/chat-switchboard/models"
)

// ── GroupStore ──────────────────────────────

type GroupStore struct{}

func NewGroupStore() *GroupStore { return &GroupStore{} }

func (s *GroupStore) Create(ctx context.Context, g *models.Group) error {
	return DB.QueryRowContext(ctx, `
		INSERT INTO groups (name, description, scope, team_id, created_by)
		VALUES ($1, $2, $3, $4, $5)
		RETURNING id, created_at, updated_at`,
		g.Name, g.Description, g.Scope,
		models.NullString(g.TeamID), g.CreatedBy,
	).Scan(&g.ID, &g.CreatedAt, &g.UpdatedAt)
}

func (s *GroupStore) GetByID(ctx context.Context, id string) (*models.Group, error) {
	var g models.Group
	var teamID sql.NullString
	err := DB.QueryRowContext(ctx, `
		SELECT g.id, g.name, g.description, g.scope, g.team_id, g.created_by,
		       g.created_at, g.updated_at,
		       (SELECT COUNT(*) FROM group_members WHERE group_id = g.id) AS member_count
		FROM groups g WHERE g.id = $1`, id).Scan(
		&g.ID, &g.Name, &g.Description, &g.Scope, &teamID, &g.CreatedBy,
		&g.CreatedAt, &g.UpdatedAt, &g.MemberCount,
	)
	if err != nil {
		return nil, err
	}
	g.TeamID = NullableStringPtr(teamID)
	return &g, nil
}

func (s *GroupStore) Update(ctx context.Context, id string, name, description *string) error {
	b := NewUpdate("groups")
	if name != nil {
		b.Set("name", *name)
	}
	if description != nil {
		b.Set("description", *description)
	}
	if !b.HasSets() {
		return nil
	}
	b.Where("id", id)
	res, err := b.Exec(DB)
	if err != nil {
		return err
	}
	if n, _ := res.RowsAffected(); n == 0 {
		return sql.ErrNoRows
	}
	return nil
}

func (s *GroupStore) Delete(ctx context.Context, id string) error {
	res, err := DB.ExecContext(ctx, "DELETE FROM groups WHERE id = $1", id)
	if err != nil {
		return err
	}
	if n, _ := res.RowsAffected(); n == 0 {
		return sql.ErrNoRows
	}
	return nil
}

// ── Scoped Listing ──────────────────────────

func (s *GroupStore) ListAll(ctx context.Context) ([]models.Group, error) {
	return queryGroups(ctx, `
		SELECT g.id, g.name, g.description, g.scope, g.team_id, g.created_by,
		       g.created_at, g.updated_at,
		       (SELECT COUNT(*) FROM group_members WHERE group_id = g.id)
		FROM groups g
		ORDER BY g.scope, g.name`)
}

func (s *GroupStore) ListForTeam(ctx context.Context, teamID string) ([]models.Group, error) {
	return queryGroups(ctx, `
		SELECT g.id, g.name, g.description, g.scope, g.team_id, g.created_by,
		       g.created_at, g.updated_at,
		       (SELECT COUNT(*) FROM group_members WHERE group_id = g.id)
		FROM groups g
		WHERE g.scope = 'team' AND g.team_id = $1
		ORDER BY g.name`, teamID)
}

func (s *GroupStore) ListForUser(ctx context.Context, userID string) ([]models.Group, error) {
	return queryGroups(ctx, `
		SELECT g.id, g.name, g.description, g.scope, g.team_id, g.created_by,
		       g.created_at, g.updated_at,
		       (SELECT COUNT(*) FROM group_members WHERE group_id = g.id)
		FROM groups g
		WHERE g.id IN (SELECT group_id FROM group_members WHERE user_id = $1)
		ORDER BY g.scope, g.name`, userID)
}

// ── Members ─────────────────────────────────

func (s *GroupStore) AddMember(ctx context.Context, groupID, userID, addedBy string) error {
	_, err := DB.ExecContext(ctx, `
		INSERT INTO group_members (group_id, user_id, added_by)
		VALUES ($1, $2, $3)
		ON CONFLICT (group_id, user_id) DO NOTHING`,
		groupID, userID, addedBy)
	return err
}

func (s *GroupStore) RemoveMember(ctx context.Context, groupID, userID string) error {
	res, err := DB.ExecContext(ctx,
		"DELETE FROM group_members WHERE group_id = $1 AND user_id = $2",
		groupID, userID)
	if err != nil {
		return err
	}
	if n, _ := res.RowsAffected(); n == 0 {
		return sql.ErrNoRows
	}
	return nil
}

func (s *GroupStore) ListMembers(ctx context.Context, groupID string) ([]models.GroupMember, error) {
	rows, err := DB.QueryContext(ctx, `
		SELECT gm.id, gm.group_id, gm.user_id, gm.added_by, gm.added_at,
		       u.username, u.email, COALESCE(u.display_name, '')
		FROM group_members gm
		JOIN users u ON u.id = gm.user_id
		WHERE gm.group_id = $1
		ORDER BY u.username`, groupID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var result []models.GroupMember
	for rows.Next() {
		var m models.GroupMember
		if err := rows.Scan(&m.ID, &m.GroupID, &m.UserID, &m.AddedBy, &m.AddedAt,
			&m.Username, &m.Email, &m.DisplayName); err != nil {
			return nil, err
		}
		result = append(result, m)
	}
	return result, rows.Err()
}

func (s *GroupStore) IsMember(ctx context.Context, groupID, userID string) (bool, error) {
	var exists bool
	err := DB.QueryRowContext(ctx, `
		SELECT EXISTS(SELECT 1 FROM group_members WHERE group_id = $1 AND user_id = $2)`,
		groupID, userID).Scan(&exists)
	return exists, err
}

func (s *GroupStore) GetUserGroupIDs(ctx context.Context, userID string) ([]string, error) {
	rows, err := DB.QueryContext(ctx,
		"SELECT group_id FROM group_members WHERE user_id = $1", userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var ids []string
	for rows.Next() {
		var id string
		if err := rows.Scan(&id); err != nil {
			return nil, err
		}
		ids = append(ids, id)
	}
	return ids, rows.Err()
}

// ── Scanners ────────────────────────────────

func queryGroups(ctx context.Context, q string, args ...interface{}) ([]models.Group, error) {
	rows, err := DB.QueryContext(ctx, q, args...)
	if err != nil {
		return nil, fmt.Errorf("queryGroups: %w", err)
	}
	defer rows.Close()

	var result []models.Group
	for rows.Next() {
		var g models.Group
		var teamID sql.NullString
		if err := rows.Scan(&g.ID, &g.Name, &g.Description, &g.Scope, &teamID,
			&g.CreatedBy, &g.CreatedAt, &g.UpdatedAt, &g.MemberCount); err != nil {
			return nil, err
		}
		g.TeamID = NullableStringPtr(teamID)
		result = append(result, g)
	}
	return result, rows.Err()
}