package repository

import (
	"context"
	"encoding/json"
	"errors"
	"time"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

// AdminRepo persists ops-admin accounts, sessions, and audit logs.
type AdminRepo struct {
	Pool *pgxpool.Pool
}

// AdminAccount is an internal operator account.
type AdminAccount struct {
	ID           uuid.UUID
	Username     string
	PasswordHash string
	Status       string
}

// CountAccounts returns non-deleted admin count.
func (r *AdminRepo) CountAccounts(ctx context.Context) (int, error) {
	var n int
	err := r.Pool.QueryRow(ctx, `
		SELECT count(*) FROM admin_accounts WHERE deleted_at IS NULL`).Scan(&n)
	return n, err
}

// CreateAccount inserts an admin account with seeded super_admin role.
func (r *AdminRepo) CreateAccount(ctx context.Context, username, hash string) (uuid.UUID, error) {
	var id uuid.UUID
	err := r.Pool.QueryRow(ctx, `
		INSERT INTO admin_accounts(username, password_hash, role_id)
		VALUES (
			$1, $2,
			(SELECT id FROM admin_roles WHERE name = 'super_admin' LIMIT 1)
		) RETURNING id`, username, hash).Scan(&id)
	return id, err
}

// FindByUsername loads an active admin by username.
func (r *AdminRepo) FindByUsername(ctx context.Context, username string) (*AdminAccount, error) {
	var a AdminAccount
	err := r.Pool.QueryRow(ctx, `
		SELECT id, username, password_hash, status
		FROM admin_accounts
		WHERE username=$1 AND deleted_at IS NULL`, username,
	).Scan(&a.ID, &a.Username, &a.PasswordHash, &a.Status)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	return &a, nil
}

// FindAccountByID loads admin by id.
func (r *AdminRepo) FindAccountByID(ctx context.Context, id uuid.UUID) (*AdminAccount, error) {
	var a AdminAccount
	err := r.Pool.QueryRow(ctx, `
		SELECT id, username, password_hash, status
		FROM admin_accounts
		WHERE id=$1 AND deleted_at IS NULL`, id,
	).Scan(&a.ID, &a.Username, &a.PasswordHash, &a.Status)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	return &a, nil
}

// CreateSession stores an opaque admin session token.
func (r *AdminRepo) CreateSession(ctx context.Context, adminID uuid.UUID, token string, expires time.Time) error {
	_, err := r.Pool.Exec(ctx, `
		INSERT INTO admin_sessions(admin_id, token, expires_at)
		VALUES ($1,$2,$3)`, adminID, token, expires)
	return err
}

// ResolveSession returns admin_id for a valid token.
func (r *AdminRepo) ResolveSession(ctx context.Context, token string) (uuid.UUID, error) {
	var id uuid.UUID
	err := r.Pool.QueryRow(ctx, `
		SELECT s.admin_id FROM admin_sessions s
		JOIN admin_accounts a ON a.id=s.admin_id AND a.deleted_at IS NULL AND a.status='active'
		WHERE s.token=$1 AND s.expires_at > now()`, token).Scan(&id)
	if errors.Is(err, pgx.ErrNoRows) {
		return uuid.Nil, errors.New("invalid session")
	}
	return id, err
}

// DeleteSession removes a session by token.
func (r *AdminRepo) DeleteSession(ctx context.Context, token string) error {
	_, err := r.Pool.Exec(ctx, `DELETE FROM admin_sessions WHERE token=$1`, token)
	return err
}

// InsertAudit appends an immutable audit row.
func (r *AdminRepo) InsertAudit(ctx context.Context, adminID uuid.UUID, action, targetType, targetID string, meta json.RawMessage) error {
	if meta == nil {
		meta = json.RawMessage(`{}`)
	}
	_, err := r.Pool.Exec(ctx, `
		INSERT INTO admin_audit_logs(admin_id, action, target_type, target_id, meta)
		VALUES ($1,$2,$3,$4,$5)`, adminID, action, targetType, targetID, meta)
	return err
}

// UserListItem is a compact user row for admin tables.
type UserListItem struct {
	ID               uuid.UUID `json:"id"`
	Status           string    `json:"status"`
	Phone            *string   `json:"phone,omitempty"`
	Nickname         *string   `json:"nickname,omitempty"`
	AskPaidQuotaLeft int       `json:"ask_paid_quota_left"`
	ProfileCount     int       `json:"profile_count"`
	MembershipActive bool      `json:"membership_active"`
	MembershipPlan   *string   `json:"membership_plan,omitempty"`
	CreatedAt        time.Time `json:"created_at"`
}

// ListUsers returns users newest first; q matches id / phone / nickname.
func (r *AdminRepo) ListUsers(ctx context.Context, q string, limit, offset int) ([]UserListItem, error) {
	if limit <= 0 || limit > 100 {
		limit = 20
	}
	if offset < 0 {
		offset = 0
	}
	rows, err := r.Pool.Query(ctx, `
		SELECT u.id, u.status, u.phone, u.nickname, u.ask_paid_quota_left, u.created_at,
			(SELECT count(*) FROM profiles p WHERE p.user_id=u.id AND p.deleted_at IS NULL) AS profile_count,
			EXISTS(
				SELECT 1 FROM memberships m
				WHERE m.user_id=u.id AND m.deleted_at IS NULL AND m.status='active' AND m.expires_at > now()
			) AS membership_active,
			(
				SELECT m.plan FROM memberships m
				WHERE m.user_id=u.id AND m.deleted_at IS NULL
				LIMIT 1
			) AS membership_plan
		FROM users u
		WHERE u.deleted_at IS NULL
		  AND (
			$1 = ''
			OR u.id::text = $1
			OR COALESCE(u.phone,'') ILIKE '%' || $1 || '%'
			OR COALESCE(u.nickname,'') ILIKE '%' || $1 || '%'
		  )
		ORDER BY u.created_at DESC
		LIMIT $2 OFFSET $3`, q, limit, offset)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []UserListItem
	for rows.Next() {
		var u UserListItem
		if err := rows.Scan(
			&u.ID, &u.Status, &u.Phone, &u.Nickname, &u.AskPaidQuotaLeft, &u.CreatedAt,
			&u.ProfileCount, &u.MembershipActive, &u.MembershipPlan,
		); err != nil {
			return nil, err
		}
		out = append(out, u)
	}
	return out, rows.Err()
}

// DashboardStats is ops overview counters.
type DashboardStats struct {
	UsersTotal       int             `json:"users_total"`
	MembershipActive int             `json:"membership_active"`
	OrdersToday      int             `json:"orders_today"`
	PaidCentsToday   int             `json:"paid_cents_today"`
	AskRepliesToday  int             `json:"ask_replies_today"`
	ProfilesTotal    int             `json:"profiles_total"`
	ReportsTotal     int             `json:"reports_total"`
	Series           []DashboardDay  `json:"series"`
	ReportsByType    []ReportTypeCnt `json:"reports_by_type"`
}

// DashboardDay is one day of trend metrics.
type DashboardDay struct {
	Day        string `json:"day"`
	NewUsers   int    `json:"new_users"`
	Orders     int    `json:"orders"`
	PaidCents  int    `json:"paid_cents"`
	AskReplies int    `json:"ask_replies"`
}

// ReportTypeCnt counts reports by type.
type ReportTypeCnt struct {
	Type  string `json:"type"`
	Count int    `json:"count"`
}

// GetDashboardStats aggregates key ops metrics.
func (r *AdminRepo) GetDashboardStats(ctx context.Context) (*DashboardStats, error) {
	s := &DashboardStats{}
	if err := r.Pool.QueryRow(ctx, `
		SELECT count(*) FROM users WHERE deleted_at IS NULL`).Scan(&s.UsersTotal); err != nil {
		return nil, err
	}
	if err := r.Pool.QueryRow(ctx, `
		SELECT count(*) FROM memberships
		WHERE deleted_at IS NULL AND status='active' AND expires_at > now()`).Scan(&s.MembershipActive); err != nil {
		return nil, err
	}
	if err := r.Pool.QueryRow(ctx, `
		SELECT count(*) FROM orders
		WHERE deleted_at IS NULL AND created_at >= date_trunc('day', now())`).Scan(&s.OrdersToday); err != nil {
		return nil, err
	}
	if err := r.Pool.QueryRow(ctx, `
		SELECT coalesce(sum(amount_cents),0) FROM orders
		WHERE deleted_at IS NULL AND status='paid' AND created_at >= date_trunc('day', now())`).Scan(&s.PaidCentsToday); err != nil {
		return nil, err
	}
	if err := r.Pool.QueryRow(ctx, `
		SELECT count(*) FROM ask_messages m
		JOIN ask_threads t ON t.id=m.thread_id AND t.deleted_at IS NULL
		WHERE m.deleted_at IS NULL AND m.role='assistant'
		  AND m.created_at >= date_trunc('day', now())`).Scan(&s.AskRepliesToday); err != nil {
		return nil, err
	}
	if err := r.Pool.QueryRow(ctx, `
		SELECT count(*) FROM profiles WHERE deleted_at IS NULL`).Scan(&s.ProfilesTotal); err != nil {
		return nil, err
	}
	if err := r.Pool.QueryRow(ctx, `
		SELECT count(*) FROM growth_reports WHERE deleted_at IS NULL`).Scan(&s.ReportsTotal); err != nil {
		return nil, err
	}

	rows, err := r.Pool.Query(ctx, `
		WITH days AS (
			SELECT generate_series(
				date_trunc('day', now()) - interval '6 day',
				date_trunc('day', now()),
				interval '1 day'
			)::date AS d
		)
		SELECT to_char(d.d, 'YYYY-MM-DD') AS day,
			(SELECT count(*) FROM users u
			 WHERE u.deleted_at IS NULL AND u.created_at::date = d.d) AS new_users,
			(SELECT count(*) FROM orders o
			 WHERE o.deleted_at IS NULL AND o.created_at::date = d.d) AS orders,
			(SELECT coalesce(sum(o.amount_cents),0) FROM orders o
			 WHERE o.deleted_at IS NULL AND o.status='paid' AND o.created_at::date = d.d) AS paid_cents,
			(SELECT count(*) FROM ask_messages m
			 JOIN ask_threads t ON t.id=m.thread_id AND t.deleted_at IS NULL
			 WHERE m.deleted_at IS NULL AND m.role='assistant' AND m.created_at::date = d.d) AS ask_replies
		FROM days d
		ORDER BY d.d ASC`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	for rows.Next() {
		var p DashboardDay
		if err := rows.Scan(&p.Day, &p.NewUsers, &p.Orders, &p.PaidCents, &p.AskReplies); err != nil {
			return nil, err
		}
		s.Series = append(s.Series, p)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}

	trows, err := r.Pool.Query(ctx, `
		SELECT type, count(*) FROM growth_reports
		WHERE deleted_at IS NULL
		GROUP BY type
		ORDER BY count(*) DESC`)
	if err != nil {
		return nil, err
	}
	defer trows.Close()
	for trows.Next() {
		var c ReportTypeCnt
		if err := trows.Scan(&c.Type, &c.Count); err != nil {
			return nil, err
		}
		s.ReportsByType = append(s.ReportsByType, c)
	}
	return s, trows.Err()
}

// UserExists reports whether user id is present.
func (r *AdminRepo) UserExists(ctx context.Context, id uuid.UUID) (bool, error) {
	var n int
	err := r.Pool.QueryRow(ctx, `
		SELECT 1 FROM users WHERE id=$1 AND deleted_at IS NULL`, id).Scan(&n)
	if errors.Is(err, pgx.ErrNoRows) {
		return false, nil
	}
	return err == nil, err
}

// ProfileBrief for admin user detail.
type ProfileBrief struct {
	ID          uuid.UUID `json:"id"`
	Relation    string    `json:"relation"`
	DisplayName string    `json:"display_name"`
	BirthDate   string    `json:"birth_date,omitempty"`
}

// ListProfilesForUser returns profile briefs.
func (r *AdminRepo) ListProfilesForUser(ctx context.Context, userID uuid.UUID) ([]ProfileBrief, error) {
	rows, err := r.Pool.Query(ctx, `
		SELECT id, relation, display_name, to_char(birth_date, 'YYYY-MM-DD')
		FROM profiles
		WHERE user_id=$1 AND deleted_at IS NULL
		ORDER BY created_at ASC`, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []ProfileBrief
	for rows.Next() {
		var p ProfileBrief
		if err := rows.Scan(&p.ID, &p.Relation, &p.DisplayName, &p.BirthDate); err != nil {
			return nil, err
		}
		out = append(out, p)
	}
	return out, rows.Err()
}

// ReportBrief for admin user detail.
type ReportBrief struct {
	ID        uuid.UUID `json:"id"`
	Type      string    `json:"type"`
	CreatedAt time.Time `json:"created_at"`
}

// ListReportsForUser returns recent growth reports.
func (r *AdminRepo) ListReportsForUser(ctx context.Context, userID uuid.UUID, limit int) ([]ReportBrief, error) {
	if limit <= 0 || limit > 50 {
		limit = 20
	}
	rows, err := r.Pool.Query(ctx, `
		SELECT id, type, created_at FROM growth_reports
		WHERE user_id=$1 AND deleted_at IS NULL
		ORDER BY created_at DESC
		LIMIT $2`, userID, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []ReportBrief
	for rows.Next() {
		var rep ReportBrief
		if err := rows.Scan(&rep.ID, &rep.Type, &rep.CreatedAt); err != nil {
			return nil, err
		}
		out = append(out, rep)
	}
	return out, rows.Err()
}

// GetUserAccount loads phone/nickname/paid ask quota for one user.
func (r *AdminRepo) GetUserAccount(ctx context.Context, userID uuid.UUID) (phone, nickname *string, paidLeft int, status string, createdAt time.Time, err error) {
	err = r.Pool.QueryRow(ctx, `
		SELECT phone, nickname, ask_paid_quota_left, status, created_at
		FROM users WHERE id=$1 AND deleted_at IS NULL`, userID,
	).Scan(&phone, &nickname, &paidLeft, &status, &createdAt)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, nil, 0, "", time.Time{}, err
	}
	return
}

// GrantAskQuotaWithAudit adds paid ask quota and writes audit.
func (r *AdminRepo) GrantAskQuotaWithAudit(ctx context.Context, adminID, userID uuid.UUID, delta int, meta json.RawMessage) (int, error) {
	if delta <= 0 {
		return 0, errors.New("delta must be positive")
	}
	tx, err := r.Pool.Begin(ctx)
	if err != nil {
		return 0, err
	}
	defer tx.Rollback(ctx)
	var left int
	err = tx.QueryRow(ctx, `
		UPDATE users SET ask_paid_quota_left = ask_paid_quota_left + $2, updated_at=now()
		WHERE id=$1 AND deleted_at IS NULL
		RETURNING ask_paid_quota_left`, userID, delta,
	).Scan(&left)
	if err != nil {
		return 0, err
	}
	if meta == nil {
		meta = json.RawMessage(`{}`)
	}
	if _, err := tx.Exec(ctx, `
		INSERT INTO admin_audit_logs(admin_id, action, target_type, target_id, meta)
		VALUES ($1,'ask_quota.grant','user',$2,$3)`, adminID, userID.String(), meta); err != nil {
		return 0, err
	}
	if err := tx.Commit(ctx); err != nil {
		return 0, err
	}
	return left, nil
}

// OrderListItem for admin order tables.
type OrderListItem struct {
	ID          uuid.UUID `json:"id"`
	UserID      uuid.UUID `json:"user_id"`
	Kind        string    `json:"kind"`
	Plan        *string   `json:"plan,omitempty"`
	AmountCents int       `json:"amount_cents"`
	Status      string    `json:"status"`
	CreatedAt   time.Time `json:"created_at"`
}

// ListOrders lists orders; optional user filter.
func (r *AdminRepo) ListOrders(ctx context.Context, userID *uuid.UUID, limit, offset int) ([]OrderListItem, error) {
	if limit <= 0 || limit > 100 {
		limit = 20
	}
	if offset < 0 {
		offset = 0
	}
	rows, err := r.Pool.Query(ctx, `
		SELECT id, user_id, kind, plan, amount_cents, status, created_at
		FROM orders
		WHERE deleted_at IS NULL
		  AND ($1::uuid IS NULL OR user_id = $1)
		ORDER BY created_at DESC
		LIMIT $2 OFFSET $3`, userID, limit, offset)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []OrderListItem
	for rows.Next() {
		var o OrderListItem
		if err := rows.Scan(&o.ID, &o.UserID, &o.Kind, &o.Plan, &o.AmountCents, &o.Status, &o.CreatedAt); err != nil {
			return nil, err
		}
		out = append(out, o)
	}
	return out, rows.Err()
}

// GrantMembershipWithAudit upserts membership and appends audit in one transaction.
func (r *AdminRepo) GrantMembershipWithAudit(
	ctx context.Context,
	adminID, userID uuid.UUID,
	plan string,
	days int,
	meta json.RawMessage,
) error {
	tx, err := r.Pool.Begin(ctx)
	if err != nil {
		return err
	}
	defer tx.Rollback(ctx)

	if _, err := tx.Exec(ctx, `
		INSERT INTO memberships(user_id, plan, status, expires_at, ask_quota_left)
		VALUES ($1,$2,'active', now() + ($3 * interval '1 day'), 100)
		ON CONFLICT (user_id) DO UPDATE SET
			plan=EXCLUDED.plan, status='active',
			expires_at=(CASE
				WHEN memberships.expires_at IS NOT NULL AND memberships.expires_at > now()
				THEN memberships.expires_at ELSE now()
			END) + ($3 * interval '1 day'),
			ask_quota_left=100, updated_at=now()`,
		userID, plan, days); err != nil {
		return err
	}
	if meta == nil {
		meta = json.RawMessage(`{}`)
	}
	if _, err := tx.Exec(ctx, `
		INSERT INTO admin_audit_logs(admin_id, action, target_type, target_id, meta)
		VALUES ($1,'membership.grant','user',$2,$3)`, adminID, userID.String(), meta); err != nil {
		return err
	}
	return tx.Commit(ctx)
}

// AuditListItem for admin audit table.
type AuditListItem struct {
	ID         uuid.UUID       `json:"id"`
	AdminID    uuid.UUID       `json:"admin_id"`
	Action     string          `json:"action"`
	TargetType string          `json:"target_type"`
	TargetID   string          `json:"target_id"`
	Meta       json.RawMessage `json:"meta"`
	CreatedAt  time.Time       `json:"created_at"`
}

// ListAuditLogs returns newest audit rows.
func (r *AdminRepo) ListAuditLogs(ctx context.Context, limit, offset int) ([]AuditListItem, error) {
	if limit <= 0 || limit > 100 {
		limit = 20
	}
	if offset < 0 {
		offset = 0
	}
	rows, err := r.Pool.Query(ctx, `
		SELECT id, admin_id, action, target_type, target_id, meta, created_at
		FROM admin_audit_logs
		ORDER BY created_at DESC
		LIMIT $1 OFFSET $2`, limit, offset)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []AuditListItem
	for rows.Next() {
		var a AuditListItem
		if err := rows.Scan(&a.ID, &a.AdminID, &a.Action, &a.TargetType, &a.TargetID, &a.Meta, &a.CreatedAt); err != nil {
			return nil, err
		}
		out = append(out, a)
	}
	return out, rows.Err()
}