package invoice

import (
	"context"
	"database/sql"
	"errors"
	"time"

	"github.com/noderunners/nip05api/internal/db"
	"github.com/noderunners/nip05api/internal/user"
)

type Repo struct{ db *db.DB }

func NewRepo(d *db.DB) *Repo { return &Repo{db: d} }

const invCols = `payment_hash, payment_request, username, pubkey, subscription_type,
    years, amount_sats, expires_at, paid, is_renewal, created_at, target_expires_at`

func scanInvoice(row interface{ Scan(...any) error }) (*PendingInvoice, error) {
	var p PendingInvoice
	var sub, expires, created string
	var paid, renewal int
	var target sql.NullString
	if err := row.Scan(&p.PaymentHash, &p.PaymentRequest, &p.Username, &p.Pubkey,
		&sub, &p.Years, &p.AmountSats, &expires, &paid, &renewal, &created, &target); err != nil {
		return nil, err
	}
	p.SubscriptionType = user.SubscriptionType(sub)
	if t, err := time.Parse(time.RFC3339, expires); err == nil {
		p.ExpiresAt = t
	}
	if t, err := time.Parse(time.RFC3339, created); err == nil {
		p.CreatedAt = t
	} else if t, err := time.Parse("2006-01-02 15:04:05", created); err == nil {
		p.CreatedAt = t
	}
	p.Paid = paid == 1
	p.IsRenewal = renewal == 1
	if target.Valid {
		p.TargetSet = true
		if target.String != "" {
			if t, err := time.Parse(time.RFC3339, target.String); err == nil {
				p.TargetExpiresAt = &t
			}
		}
	}
	return &p, nil
}

func (r *Repo) Insert(ctx context.Context, p *PendingInvoice) error {
	var target any
	if p.TargetSet {
		if p.TargetExpiresAt != nil {
			target = p.TargetExpiresAt.UTC().Format(time.RFC3339)
		} else {
			target = ""
		}
	}
	_, err := r.db.ExecContext(ctx, `INSERT INTO pending_invoices
        (payment_hash, payment_request, username, pubkey, subscription_type,
         years, amount_sats, expires_at, paid, is_renewal, target_expires_at)
        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
		p.PaymentHash, p.PaymentRequest, p.Username, p.Pubkey,
		string(p.SubscriptionType), p.Years, p.AmountSats,
		p.ExpiresAt.UTC().Format(time.RFC3339),
		boolToInt(p.Paid), boolToInt(p.IsRenewal), target)
	return err
}

func (r *Repo) Get(ctx context.Context, hash string) (*PendingInvoice, error) {
	row := r.db.QueryRowContext(ctx, `SELECT `+invCols+` FROM pending_invoices WHERE payment_hash = ?`, hash)
	p, err := scanInvoice(row)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrInvoiceNotFound
	}
	return p, err
}

func (r *Repo) MarkPaid(ctx context.Context, hash string) error {
	_, err := r.db.ExecContext(ctx, `UPDATE pending_invoices SET paid = 1 WHERE payment_hash = ?`, hash)
	return err
}

// SetTargetIfUnset writes target_expires_at only when currently NULL.
// Returns true if this call won the race. Lifetime is encoded as empty string,
// allowing the caller to distinguish "not yet set" (NULL) from "set to nil".
func (r *Repo) SetTargetIfUnset(ctx context.Context, hash string, target *time.Time) (bool, error) {
	stored := ""
	if target != nil {
		stored = target.UTC().Format(time.RFC3339)
	}
	res, err := r.db.ExecContext(ctx,
		`UPDATE pending_invoices SET target_expires_at = ? WHERE payment_hash = ? AND target_expires_at IS NULL`,
		stored, hash)
	if err != nil {
		return false, err
	}
	n, _ := res.RowsAffected()
	return n == 1, nil
}

// ClaimPaid atomically transitions paid 0 → 1. Returns true if the caller
// performed the transition (i.e. it was unpaid before this call).
func (r *Repo) ClaimPaid(ctx context.Context, hash string) (bool, error) {
	res, err := r.db.ExecContext(ctx,
		`UPDATE pending_invoices SET paid = 1 WHERE payment_hash = ? AND paid = 0`, hash)
	if err != nil {
		return false, err
	}
	n, _ := res.RowsAffected()
	return n == 1, nil
}

func (r *Repo) ListUnpaid(ctx context.Context) ([]*PendingInvoice, error) {
	rows, err := r.db.QueryContext(ctx, `SELECT `+invCols+` FROM pending_invoices
        WHERE paid = 0 AND expires_at > ?`,
		time.Now().UTC().Format(time.RFC3339))
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := []*PendingInvoice{}
	for rows.Next() {
		p, err := scanInvoice(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, p)
	}
	return out, rows.Err()
}

// HasUnpaidForUsername returns true if there is an active unpaid invoice for the username.
func (r *Repo) HasUnpaidForUsername(ctx context.Context, username string) (bool, error) {
	var count int
	err := r.db.QueryRowContext(ctx, `SELECT COUNT(1) FROM pending_invoices
        WHERE username = ? COLLATE NOCASE AND paid = 0 AND expires_at > ?`,
		username, time.Now().UTC().Format(time.RFC3339)).Scan(&count)
	return count > 0, err
}

// HasUnpaidForPubkey returns true if there is an active unpaid invoice for the pubkey.
func (r *Repo) HasUnpaidForPubkey(ctx context.Context, pubkey string) (bool, error) {
	var count int
	err := r.db.QueryRowContext(ctx, `SELECT COUNT(1) FROM pending_invoices
        WHERE pubkey = ? AND paid = 0 AND expires_at > ?`,
		pubkey, time.Now().UTC().Format(time.RFC3339)).Scan(&count)
	return count > 0, err
}

// GetActiveUnpaidByPubkey returns the most recent unpaid, unexpired invoice for the pubkey, or nil if none.
func (r *Repo) GetActiveUnpaidByPubkey(ctx context.Context, pubkey string) (*PendingInvoice, error) {
	row := r.db.QueryRowContext(ctx, `SELECT `+invCols+` FROM pending_invoices
        WHERE pubkey = ? AND paid = 0 AND expires_at > ?
        ORDER BY created_at DESC LIMIT 1`,
		pubkey, time.Now().UTC().Format(time.RFC3339))
	p, err := scanInvoice(row)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	return p, nil
}

// DeleteActiveUnpaidForPubkey removes all unpaid, unexpired invoices for the pubkey so a new
// invoice can be issued when the user switches plan (replacing the previous Bolt11).
func (r *Repo) DeleteActiveUnpaidForPubkey(ctx context.Context, pubkey string) error {
	_, err := r.db.ExecContext(ctx,
		`DELETE FROM pending_invoices WHERE pubkey = ? AND paid = 0 AND expires_at > ?`,
		pubkey, time.Now().UTC().Format(time.RFC3339))
	return err
}

func (r *Repo) PurgeOldUnpaid(ctx context.Context) error {
	cutoff := time.Now().UTC().Add(-1 * time.Hour).Format(time.RFC3339)
	_, err := r.db.ExecContext(ctx, `DELETE FROM pending_invoices WHERE paid = 0 AND expires_at < ?`, cutoff)
	return err
}

func boolToInt(b bool) int {
	if b {
		return 1
	}
	return 0
}