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.
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)
		VALUES ($1,$2) 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"`
	CreatedAt time.Time `json:"created_at"`
}

// ListUsers returns users newest first; q matches id when UUID.
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 id, status, created_at FROM users
		WHERE deleted_at IS NULL
		  AND ($1 = '' OR id::text = $1)
		ORDER BY 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.CreatedAt); err != nil {
			return nil, err
		}
		out = append(out, u)
	}
	return out, rows.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"`
}

// 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 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); err != nil {
			return nil, err
		}
		out = append(out, p)
	}
	return out, rows.Err()
}

// 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()
}