<?php
require_once __DIR__ . '/DocumentNumberManager.php';
require_once __DIR__ . '/../classes_ac/PostingWindowGuard.php';

/**
 * QuotationManager
 *
 * All read/write operations for td_quotation and td_quotation_item.
 *
 * Status flow:  0=draft → 1=sent → 2=accepted → 5=converted
 *                          1/2/3  ← reopen    3=rejected
 *               0/1       → -1=cancelled
 *
 * Tax: tax_amount is stored per line at full precision (decimal 18,4).
 *      document.tax = ROUND(SUM(items.tax_amount), 2) — never passed from caller.
 *
 * Write methods do NOT manage their own DB transactions.
 * Callers must wrap multi-step operations inside dbTransaction().
 */
class QuotationManager
{
    private PDO $pdo;
    private int $company_id;

    public function __construct(PDO $pdo, int $company_id)
    {
        $this->pdo        = $pdo;
        $this->company_id = $company_id;
    }

    // ─────────────────────────────────────────────────────────────
    // Private helpers
    // ─────────────────────────────────────────────────────────────

    private function generateNumber(array $data = []): string
    {
        return (new DocumentNumberManager($this->pdo, $this->company_id))
            ->resolveNumber($data, 'quotation', 'td_quotation', 'quotation_number');
    }

    /**
     * Derive document-level totals from line items.
     * tax = ROUND(SUM(items.tax_amount), 2) — never accepted from caller.
     */
    private function computeTotals(array $items, float $discount): array
    {
        $subtotal   = array_sum(array_map(fn($i) => (float)($i['total_price'] ?? 0), $items));
        $tax        = round(array_sum(array_map(fn($i) => (float)($i['tax_amount'] ?? 0), $items)), 2);
        $grand      = max(0, $subtotal - $discount + $tax);
        return [round($subtotal, 4), $tax, round($grand, 4)];
    }

    /** DELETE + INSERT all line items. converted_qty is always preserved or reset to 0 on create. */
    private function syncItems(int $quotation_id, array $items): void
    {
        $this->pdo->prepare(
            "DELETE FROM td_quotation_item
             WHERE quotation_id = :qid AND company_id = :cid"
        )->execute([':qid' => $quotation_id, ':cid' => $this->company_id]);

        $sth = $this->pdo->prepare(
            "INSERT INTO td_quotation_item
                (company_id, quotation_id, item_id, product_sku, product_name,
                 quantity, unit_price, total_price, tax_amount, tax_rate, converted_qty)
             VALUES
                (:company_id, :quotation_id, :item_id, :product_sku, :product_name,
                 :quantity, :unit_price, :total_price, :tax_amount, :tax_rate, 0)"
        );
        foreach ($items as $pos => $item) {
            $sth->execute([
                ':company_id'   => $this->company_id,
                ':quotation_id' => $quotation_id,
                ':item_id'      => $pos + 1,
                ':product_sku'  => $item['product_sku']  ?? '',
                ':product_name' => $item['product_name'] ?? '',
                ':quantity'     => (float)($item['quantity']   ?? 0),
                ':unit_price'   => (float)($item['unit_price'] ?? 0),
                ':total_price'  => (float)($item['total_price'] ?? 0),
                ':tax_amount'   => (float)($item['tax_amount']  ?? 0),
                ':tax_rate'     => (float)($item['tax_rate']    ?? 0),
            ]);
        }
    }

    // ─────────────────────────────────────────────────────────────
    // Read
    // ─────────────────────────────────────────────────────────────

    public function getList(): array
    {
        $sth = $this->pdo->prepare(
            "SELECT q.*, COALESCE(c.contact_name, '') AS contact_name,
                    (SELECT COUNT(*) FROM td_quotation_item i
                     WHERE i.company_id   = q.company_id
                       AND i.quotation_id = q.id) AS item_count
             FROM td_quotation q
             LEFT JOIN md_contact c
               ON c.id = q.contact_id AND c.company_id = q.company_id
             WHERE q.company_id = :cid
             ORDER BY q.id DESC"
        );
        $sth->execute([':cid' => $this->company_id]);
        return $sth->fetchAll(PDO::FETCH_ASSOC);
    }

    public function getStats(): array
    {
        $sth = $this->pdo->prepare(
            "SELECT
                COUNT(*) AS total,
                SUM(status = 0) AS draft,
                SUM(status = 1) AS sent,
                SUM(status = 2) AS accepted,
                SUM(status = 3) AS rejected
             FROM td_quotation
             WHERE company_id = :cid"
        );
        $sth->execute([':cid' => $this->company_id]);
        return $sth->fetch(PDO::FETCH_ASSOC) ?: [];
    }

    public function getById(int $id): array|false
    {
        $sth = $this->pdo->prepare(
            "SELECT q.*, COALESCE(c.contact_name, '') AS contact_name
             FROM td_quotation q
             LEFT JOIN md_contact c
               ON c.id = q.contact_id AND c.company_id = q.company_id
             WHERE q.id = :id AND q.company_id = :cid
             LIMIT 1"
        );
        $sth->execute([':id' => $id, ':cid' => $this->company_id]);
        $row = $sth->fetch(PDO::FETCH_ASSOC);
        if (!$row) return false;

        $sth2 = $this->pdo->prepare(
            "SELECT *, (quantity - converted_qty) AS remaining_qty
             FROM td_quotation_item
             WHERE quotation_id = :qid AND company_id = :cid
             ORDER BY item_id"
        );
        $sth2->execute([':qid' => $id, ':cid' => $this->company_id]);
        $row['items']           = $sth2->fetchAll(PDO::FETCH_ASSOC);
        $row['total_remaining'] = array_sum(array_column($row['items'], 'remaining_qty'));

        $sth3 = $this->pdo->prepare(
            "SELECT id, order_number, status, grand_total, created_at
             FROM td_order
             WHERE company_id = :cid
               AND source     = 'quotation'
               AND source_id  = :qid
               AND status    != -1
             ORDER BY id"
        );
        $sth3->execute([':cid' => $this->company_id, ':qid' => $id]);
        $row['linked_orders'] = $sth3->fetchAll(PDO::FETCH_ASSOC);

        return $row;
    }

    // ─────────────────────────────────────────────────────────────
    // Write
    // ─────────────────────────────────────────────────────────────

    /**
     * Create (id=0) or update an existing draft quotation.
     *
     * @param array $data  Keys: id, contact_id, department_id, quotation_date,
     *                           valid_until, items (array), discount, notes.
     *                           Each item must include tax_amount.
     * @return int  The quotation id (new or existing).
     */
    public function save(array $data, array $logging): int
    {
        $id       = (int)($data['id'] ?? 0);
        $items    = $data['items'] ?? [];
        $discount = (float)($data['discount'] ?? 0);

        $quotation_date = (string)($data['quotation_date'] ?? '');
        $valid_until    = (string)($data['valid_until']    ?? '');
        if ((int)($data['contact_id'] ?? 0) <= 0) {
            throw new Exception('Contact is required.');
        }
        if ($quotation_date === '') {
            throw new Exception('Quotation date is required.');
        }
        if ($valid_until !== '' && $valid_until < $quotation_date) {
            throw new Exception('Valid until cannot be earlier than the quotation date.');
        }
        if ((int)($data['department_id'] ?? 0) <= 0) {
            throw new Exception('Department is required.');
        }
        if (empty($items)) {
            throw new Exception('At least one line item is required.');
        }

        [$subtotal, $tax, $grand] = $this->computeTotals($items, $discount);

        if ($id === 0) {
            $number = $this->generateNumber($data);
            $log    = [array_merge($logging, ['action' => 'create_quotation'])];

            $this->pdo->prepare(
                "INSERT INTO td_quotation
                    (company_id, uuid, quotation_number, contact_id, department_id,
                     quotation_date, valid_until, status,
                     subtotal, discount, tax, grand_total, notes, `log`, created_at)
                 VALUES
                    (:cid, :uuid, :num, :contact_id, :department_id,
                     :qdate, :valid_until, 0,
                     :sub, :disc, :tax, :grand, :notes, :log, NOW())"
            )->execute([
                ':cid'           => $this->company_id,
                ':uuid'          => bin2hex(random_bytes(16)),
                ':num'           => $number,
                ':contact_id'    => (int)($data['contact_id']    ?? 0),
                ':department_id' => (int)($data['department_id'] ?? 0),
                ':qdate'         => $data['quotation_date'] ?: null,
                ':valid_until'   => $data['valid_until']    ?: null,
                ':sub'           => $subtotal,
                ':disc'          => $discount,
                ':tax'           => $tax,
                ':grand'         => $grand,
                ':notes'         => $data['notes'] ?? '',
                ':log'           => json_encode($log),
            ]);

            $id = (int)$this->pdo->lastInsertId();
            $this->syncItems($id, $items);
            return $id;
        }

        // Update — only allowed on draft (status = 0)
        $sth = $this->pdo->prepare(
            "SELECT status, `log` FROM td_quotation
             WHERE id = :id AND company_id = :cid LIMIT 1"
        );
        $sth->execute([':id' => $id, ':cid' => $this->company_id]);
        $row = $sth->fetch(PDO::FETCH_ASSOC);
        if (!$row) throw new Exception('Quotation not found.');
        if ((int)$row['status'] !== 0) throw new Exception('Only draft quotations can be edited.');

        $log   = json_decode($row['log'] ?: '[]', true);
        $log[] = array_merge($logging, ['action' => 'update_quotation']);

        $this->pdo->prepare(
            "UPDATE td_quotation SET
                contact_id     = :contact_id,
                department_id  = :department_id,
                quotation_date = :qdate,
                valid_until    = :valid_until,
                subtotal       = :sub,
                discount       = :disc,
                tax            = :tax,
                grand_total    = :grand,
                notes          = :notes,
                `log`          = :log
             WHERE id = :id AND company_id = :cid"
        )->execute([
            ':contact_id'    => (int)($data['contact_id']    ?? 0),
            ':department_id' => (int)($data['department_id'] ?? 0),
            ':qdate'         => $data['quotation_date'] ?: null,
            ':valid_until'   => $data['valid_until']    ?: null,
            ':sub'           => $subtotal,
            ':disc'          => $discount,
            ':tax'           => $tax,
            ':grand'         => $grand,
            ':notes'         => $data['notes'] ?? '',
            ':log'           => json_encode($log),
            ':id'            => $id,
            ':cid'           => $this->company_id,
        ]);

        $this->syncItems($id, $items);
        return $id;
    }

    /**
     * Transition quotation status.
     * Valid actions: send, accept, reject, reopen, cancel.
     */
    public function updateStatus(int $id, string $action, array $logging): void
    {
        $transitions = [
            'send'   => ['from' => [0],       'to' => 1,  'label' => 'Sent'],
            'accept' => ['from' => [1],        'to' => 2,  'label' => 'Accepted'],
            'reject' => ['from' => [1],        'to' => 3,  'label' => 'Rejected'],
            'reopen' => ['from' => [1, 2, 3],  'to' => 0,  'label' => 'Draft'],
            'cancel' => ['from' => [0, 1],     'to' => -1, 'label' => 'Cancelled'],
        ];

        if (!isset($transitions[$action])) throw new Exception('Invalid action.');

        $sth = $this->pdo->prepare(
            "SELECT status FROM td_quotation WHERE id = :id AND company_id = :cid LIMIT 1"
        );
        $sth->execute([':id' => $id, ':cid' => $this->company_id]);
        $row = $sth->fetch(PDO::FETCH_ASSOC);
        if (!$row) throw new Exception('Quotation not found.');

        $t = $transitions[$action];
        if (!in_array((int)$row['status'], $t['from'], true)) {
            throw new Exception('Transition not allowed from current status.');
        }

        if ($action === 'reopen') {
            $sth2 = $this->pdo->prepare(
                "SELECT COUNT(*) FROM td_quotation_item
                 WHERE quotation_id = :qid AND company_id = :cid AND converted_qty > 0"
            );
            $sth2->execute([':qid' => $id, ':cid' => $this->company_id]);
            if ((int)$sth2->fetchColumn() > 0) {
                throw new Exception('Cannot reopen — one or more items have already been converted to an order.');
            }
        }

        $this->pdo->prepare(
            "UPDATE td_quotation SET status = :status WHERE id = :id AND company_id = :cid"
        )->execute([':status' => $t['to'], ':id' => $id, ':cid' => $this->company_id]);
    }

    /**
     * Soft-delete a quotation by negating company_id on the header and all items.
     * Blocked if any sales order (not yet soft-deleted) was converted from this quotation.
     */
    public function softDelete(int $id): void
    {
        $sth = $this->pdo->prepare(
            "SELECT id, quotation_date FROM td_quotation WHERE id = :id AND company_id = :cid LIMIT 1"
        );
        $sth->execute([':id' => $id, ':cid' => $this->company_id]);
        $row = $sth->fetch(PDO::FETCH_ASSOC);
        if (!$row) throw new Exception('Quotation not found.');

        global $pdo1;
        if (isset($pdo1) && $pdo1 instanceof PDO) {
            $guard = new PostingWindowGuard($pdo1, $this->company_id);
            $guard->assertOpenDate($row['quotation_date'] ?: date('Y-m-d'), 'Quotation deletion');
        }

        $sth2 = $this->pdo->prepare(
            "SELECT COUNT(*) FROM td_order
             WHERE company_id = :cid AND source = 'quotation' AND source_id = :id"
        );
        $sth2->execute([':cid' => $this->company_id, ':id' => $id]);
        if ((int)$sth2->fetchColumn() > 0) {
            throw new Exception('Cannot delete — this quotation has linked sales orders. Delete the orders first.');
        }

        $this->pdo->prepare(
            "UPDATE td_quotation_item SET company_id = company_id * -1
             WHERE quotation_id = :id AND company_id = :cid"
        )->execute([':id' => $id, ':cid' => $this->company_id]);

        $this->pdo->prepare(
            "UPDATE td_quotation SET company_id = company_id * -1
             WHERE id = :id AND company_id = :cid"
        )->execute([':id' => $id, ':cid' => $this->company_id]);
    }

    /**
     * Increment converted_qty per item after a successful order conversion.
     * Automatically sets quotation status = 5 when all items are fully converted.
     *
     * @param array $validated  Each entry: ['item_id' => int, 'quantity' => float]
     */
    public function incrementConvertedQty(int $quotation_id, array $validated): void
    {
        $upd = $this->pdo->prepare(
            "UPDATE td_quotation_item
             SET converted_qty = converted_qty + :qty
             WHERE quotation_id = :qid AND item_id = :item_id AND company_id = :cid"
        );
        foreach ($validated as $v) {
            $upd->execute([
                ':qty'     => $v['quantity'],
                ':qid'     => $quotation_id,
                ':item_id' => $v['item_id'],
                ':cid'     => $this->company_id,
            ]);
        }

        $sth = $this->pdo->prepare(
            "SELECT COUNT(*) FROM td_quotation_item
             WHERE quotation_id = :qid AND company_id = :cid
               AND converted_qty < quantity - 0.000001"
        );
        $sth->execute([':qid' => $quotation_id, ':cid' => $this->company_id]);
        if ((int)$sth->fetchColumn() === 0) {
            $this->pdo->prepare(
                "UPDATE td_quotation SET status = 5 WHERE id = :id AND company_id = :cid"
            )->execute([':id' => $quotation_id, ':cid' => $this->company_id]);
        }
    }
}