<?php

/**
 * StockManager
 *
 * Encapsulates read operations for ICS stock transactions:
 * - Stock list by type (in / out / transfer)
 * - Single record retrieval for stock_in, stock_out, transfer
 *
 * Write operations (manage_stock_in, manage_stock_out, manage_stock_transfer)
 * are handled in their engine files via WarehouseManager.
 */
class StockManager {

    private $pdo;
    private $company_id;

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

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

    /**
     * Resolve warehouse name by ID and return the td_stock_<wh> table name.
     * Throws if warehouse not found.
     */
    private function resolveTable(int $warehouse_id): string
    {
        $sth = $this->pdo->prepare(
            "SELECT warehouse_name FROM md_warehouse
             WHERE company_id = :company_id AND id = :id"
        );
        $sth->execute([':company_id' => $this->company_id, ':id' => $warehouse_id]);
        $name = $sth->fetchColumn();

        if (!$name) {
            throw new Exception("Warehouse not found.");
        }

        $safe = preg_replace('/[^a-zA-Z0-9_]/', '', $name);
        return "td_stock_{$safe}";
    }

    // ─────────────────────────────────────────────────────────────
    // Stock list queries
    // ─────────────────────────────────────────────────────────────

    /**
     * List all stock records of a given type for a warehouse.
     * type: 'in' | 'out' | 'transfer'
     */
    public function getStockList(int $warehouse_id, string $type): array
    {
        $table  = $this->resolveTable($warehouse_id);
        $column = $type === 'out' ? 'ROUND(a.out, 2)' : 'ROUND(a.in, 2)';

        // transfer list shows outbound side only (out > 0)
        $extra_cond = ($type === 'transfer') ? 'AND a.out > 0' : '';

        $sth = $this->pdo->prepare(
            "SELECT a.*, {$column} AS quantity, b.product_name
             FROM `{$table}` a
             LEFT JOIN md_product b
                 ON a.company_id  = b.company_id
                AND a.product_sku = b.sku
             WHERE a.company_id = :company_id
               AND a.type       = :type
               {$extra_cond}
             ORDER BY a.date DESC"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':type'       => $type,
        ]);
        return $sth->fetchAll(PDO::FETCH_ASSOC);
    }

    // ─────────────────────────────────────────────────────────────
    // Single record retrieval
    // ─────────────────────────────────────────────────────────────

    /**
     * Fetch a single stock_in record with product and contact name,
     * plus lot expiry date if applicable.
     */
    public function getStockInById(int $warehouse_id, int $id): array|false
    {
        $table = $this->resolveTable($warehouse_id);

        $sth = $this->pdo->prepare(
            "SELECT a.*, a.in AS quantity,
                    b.contact_name,
                    c.product_name,
                    d.expiry_date
             FROM `{$table}` a
             LEFT JOIN md_contact b
                 ON a.company_id = b.company_id AND a.contact_id = b.id
             LEFT JOIN md_product c
                 ON a.company_id = c.company_id AND a.product_sku = c.sku
             LEFT JOIN md_lot d
                 ON a.company_id  = d.company_id
                AND a.product_sku = d.product_sku
                AND a.lot_number  = d.lot_number
             WHERE a.company_id = :company_id AND a.id = :id"
        );
        $sth->execute([':company_id' => $this->company_id, ':id' => $id]);
        return $sth->fetch(PDO::FETCH_ASSOC);
    }

    /**
     * Fetch a single stock_out record with product and contact name.
     */
    public function getStockOutById(int $warehouse_id, int $id): array|false
    {
        $table = $this->resolveTable($warehouse_id);

        $sth = $this->pdo->prepare(
            "SELECT a.*, a.out AS quantity,
                    b.contact_name,
                    c.product_name
             FROM `{$table}` a
             LEFT JOIN md_contact b
                 ON a.company_id = b.company_id AND a.contact_id = b.id
             LEFT JOIN md_product c
                 ON a.company_id = c.company_id AND a.product_sku = c.sku
             WHERE a.company_id = :company_id AND a.id = :id"
        );
        $sth->execute([':company_id' => $this->company_id, ':id' => $id]);
        return $sth->fetch(PDO::FETCH_ASSOC);
    }

    /**
     * Fetch a transfer record pair — the outbound row plus its paired
     * inbound row resolved via ref_warehouse + uuid.
     * Returns the outbound row with a 'ref' key containing the inbound row.
     */
    public function getTransferById(int $warehouse_id, int $id): array|false
    {
        $table = $this->resolveTable($warehouse_id);

        // Fetch the outbound (from) row
        $sth = $this->pdo->prepare(
            "SELECT a.*, a.out AS quantity,
                    b.contact_name,
                    c.product_name
             FROM `{$table}` a
             LEFT JOIN md_contact b
                 ON a.company_id = b.company_id AND a.contact_id = b.id
             LEFT JOIN md_product c
                 ON a.company_id = c.company_id AND a.product_sku = c.sku
             WHERE a.company_id = :company_id AND a.id = :id"
        );
        $sth->execute([':company_id' => $this->company_id, ':id' => $id]);
        $output = $sth->fetch(PDO::FETCH_ASSOC);

        if (!$output) return false;

        // Resolve the inbound (to) row via ref_warehouse + uuid
        $to_warehouse_id = (int)$output['ref_warehouse'];
        $to_table        = $this->resolveTable($to_warehouse_id);

        $sth = $this->pdo->prepare(
            "SELECT a.*, a.in AS quantity,
                    b.contact_name,
                    c.product_name
             FROM `{$to_table}` a
             LEFT JOIN md_contact b
                 ON a.company_id = b.company_id AND a.contact_id = b.id
             LEFT JOIN md_product c
                 ON a.company_id = b.company_id AND a.product_sku = c.sku
             WHERE a.company_id = :company_id AND a.uuid = :uuid"
        );
        $sth->execute([':company_id' => $this->company_id, ':uuid' => $output['uuid']]);
        $output['ref'] = $sth->fetch(PDO::FETCH_ASSOC);

        return $output;
    }


    // ─────────────────────────────────────────────────────────────
    // Stock write operations
    // ─────────────────────────────────────────────────────────────

    /**
     * Insert or update a stock_in record.
     * On insert: upserts md_lot, inserts td_stock row, occupies rack, adjusts balance.
     * On update: updates metadata (contact, description, log) only.
     * Must be called inside dbTransaction() by the caller.
     */
    public function saveStockIn(array $data, array $logging, string $uuid): void
    {
        $id           = (int)$data['id'];
        $warehouse_id = (int)$data['warehouse'];
        $whMgmt       = new WarehouseManager($this->pdo, $this->company_id);

        $ctx       = $whMgmt->getStockContext($warehouse_id, $id);
        $row       = $ctx['row'] ?? [];
        $table     = $ctx['table'];
        $table_log = json_decode($row['log'] ?? '[]', true) ?: [];
        $table_log[] = $logging;

        if ($id > 0) {

            $this->pdo->prepare(
                "UPDATE `$table` SET
                    `contact_id`  = :contact_id,
                    `description` = :description,
                    `log`         = :log
                WHERE id = :id AND company_id = :company_id"
            )->execute([
                ':id'          => $id,
                ':company_id'  => $this->company_id,
                ':contact_id'  => (int)$data['contact_id'],
                ':description' => $data['description'],
                ':log'         => json_encode($table_log),
            ]);

        } else {

            $lot_number  = $data['lot_number']  ?: null;
            $expiry_date = $data['expiry_date'] ?: null;

            // Upsert md_lot if lot + expiry provided
            if ($lot_number && $expiry_date) {
                $this->pdo->prepare(
                    "INSERT INTO md_lot (company_id, product_sku, lot_number, expiry_date)
                    VALUES (:company_id, :product_sku, :lot_number, :expiry_date)
                    ON DUPLICATE KEY UPDATE expiry_date = expiry_date"
                )->execute([
                    ':company_id'  => $this->company_id,
                    ':product_sku' => $data['product_sku'],
                    ':lot_number'  => $lot_number,
                    ':expiry_date' => $expiry_date,
                ]);
            }

            $this->pdo->prepare(
                "INSERT INTO `$table`
                    (uuid, company_id, `date`, product_sku, `in`, zone, aisle, rack,
                    contact_id, `description`, `log`, `type`, lot_number, serial_number)
                VALUES
                    (:uuid, :company_id, :date, :product_sku, :quantity, :zone, :aisle, :rack,
                    :contact_id, :description, :log, 'in', :lot_number, :serial_number)"
            )->execute([
                ':uuid'          => $uuid,
                ':company_id'    => $this->company_id,
                ':date'          => date('Y-m-d H:i:s'),
                ':product_sku'   => $data['product_sku'],
                ':quantity'      => $data['quantity'],
                ':zone'          => $data['zone'],
                ':aisle'         => $data['aisle'],
                ':rack'          => $data['rack'],
                ':contact_id'    => (int)$data['contact_id'],
                ':description'   => $data['description'],
                ':log'           => json_encode($table_log),
                ':lot_number'    => $lot_number,
                ':serial_number' => $data['serial_number'] ?: null,
            ]);

            $td_stock_id = (int)$this->pdo->lastInsertId();

            $whMgmt->occupyRack(
                $warehouse_id,
                $data['zone'], $data['aisle'], $data['rack'],
                $data['product_sku'],
                $td_stock_id
            );

            $whMgmt->adjustBalance(
                'in',
                $warehouse_id,
                $data['product_sku'],
                $row['in'] ?? 0,
                $data['quantity']
            );
        }
    }

    /**
     * Insert or update a stock_out record.
     * On insert: validates rack, inserts td_stock row, releases rack, adjusts balance.
     * On update: updates metadata (contact, description, log) only.
     * Must be called inside dbTransaction() by the caller.
     */
    public function saveStockOut(array $data, array $logging, string $uuid): void
    {
        $id           = (int)$data['id'];
        $warehouse_id = (int)$data['warehouse'];
        $whMgmt       = new WarehouseManager($this->pdo, $this->company_id);

        $ctx       = $whMgmt->getStockContext($warehouse_id, $id);
        $row       = $ctx['row'] ?? [];
        $table     = $ctx['table'];
        $table_log = json_decode($row['log'] ?? '[]', true) ?: [];
        $table_log[] = $logging;

        if ($id > 0) {

            $this->pdo->prepare(
                "UPDATE `$table` SET
                    `contact_id`  = :contact_id,
                    `description` = :description,
                    `log`         = :log
                WHERE id = :id AND company_id = :company_id"
            )->execute([
                ':id'          => $id,
                ':company_id'  => $this->company_id,
                ':contact_id'  => (int)$data['contact_id'],
                ':description' => $data['description'],
                ':log'         => json_encode($table_log),
            ]);

        } else {

            $source_stock = $whMgmt->getRackStock(
                $warehouse_id,
                $data['zone'], $data['aisle'], $data['rack']
            );

            if (!$source_stock) {
                throw new Exception(
                    "Rack {$data['zone']}-{$data['aisle']}-{$data['rack']} is empty — nothing to take out."
                );
            }

            if ($source_stock['product_sku'] !== $data['product_sku']) {
                throw new Exception(
                    "Rack holds {$source_stock['product_sku']}, not {$data['product_sku']}."
                );
            }

            if (!empty($data['lot_number']) && $source_stock['lot_number'] !== $data['lot_number']) {
                throw new Exception(
                    "Rack holds lot '{$source_stock['lot_number']}', not '{$data['lot_number']}'."
                );
            }

            if (!empty($data['serial_number']) && $source_stock['serial_number'] !== $data['serial_number']) {
                throw new Exception(
                    "Rack holds serial '{$source_stock['serial_number']}', not '{$data['serial_number']}'."
                );
            }

            $quantity      = (int)$source_stock['in'];
            $ref_id        = (int)$source_stock['id'];
            $lot_number    = $source_stock['lot_number']    ?? null;
            $serial_number = $source_stock['serial_number'] ?? null;

            $this->pdo->prepare(
                "INSERT INTO `$table`
                    (uuid, company_id, `date`, product_sku, `out`, zone, aisle, rack,
                    contact_id, `description`, `log`, `type`, ref_id, lot_number, serial_number)
                VALUES
                    (:uuid, :company_id, :date, :product_sku, :quantity, :zone, :aisle, :rack,
                    :contact_id, :description, :log, 'out', :ref_id, :lot_number, :serial_number)"
            )->execute([
                ':uuid'          => $uuid,
                ':company_id'    => $this->company_id,
                ':date'          => date('Y-m-d H:i:s'),
                ':product_sku'   => $data['product_sku'],
                ':quantity'      => $quantity,
                ':zone'          => $data['zone'],
                ':aisle'         => $data['aisle'],
                ':rack'          => $data['rack'],
                ':contact_id'    => (int)$data['contact_id'],
                ':description'   => $data['description'],
                ':log'           => json_encode($table_log),
                ':ref_id'        => $ref_id,
                ':lot_number'    => $lot_number,
                ':serial_number' => $serial_number,
            ]);

            $whMgmt->releaseRack(
                $warehouse_id,
                $data['zone'], $data['aisle'], $data['rack']
            );

            $whMgmt->adjustBalance(
                'out',
                $warehouse_id,
                $data['product_sku'],
                $row['out'] ?? 0,
                $quantity
            );
        }
    }

    /**
     * Insert or update a stock transfer record pair.
     * On insert: validates source rack, inserts paired td_stock rows, moves rack state, adjusts both balances.
     * On update: updates metadata (contact, description, log) on both rows only.
     * Must be called inside dbTransaction() by the caller.
     */
    public function saveStockTransfer(array $data, array $logging, string $uuid): void
    {
        $id     = (int)($data['id'] ?? 0);
        $whMgmt = new WarehouseManager($this->pdo, $this->company_id);

        $contact_id  = (int)($data['contact_id']  ?? 0);
        $description =      ($data['description'] ?? '');

        if ($id > 0) {

            $from_warehouse = (int)($data['warehouse_from'] ?? 0);
            $to_warehouse   = (int)($data['warehouse_to']   ?? 0);

            $from_ctx = $whMgmt->getStockContext($from_warehouse, $id);
            $from_row = $from_ctx['row'];

            if (!$from_row) {
                throw new Exception("Transfer record not found.");
            }

            $to_id  = (int)$from_row['ref_id'];
            $to_ctx = $whMgmt->getStockContext($to_warehouse, $to_id);
            $to_row = $to_ctx['row'];

            if (!$to_row) {
                throw new Exception("Paired destination record missing — data integrity issue.");
            }

            $from_log   = json_decode($from_row['log'] ?? '[]', true) ?: [];
            $from_log[] = $logging;
            $to_log     = json_decode($to_row['log']   ?? '[]', true) ?: [];
            $to_log[]   = $logging;

            $this->pdo->prepare(
                "UPDATE `{$from_ctx['table']}` SET
                    contact_id  = :contact_id,
                    description = :description,
                    `log`       = :log
                WHERE id = :id AND company_id = :company_id"
            )->execute([
                ':contact_id'  => $contact_id,
                ':description' => $description,
                ':log'         => json_encode($from_log),
                ':id'          => $id,
                ':company_id'  => $this->company_id,
            ]);

            $this->pdo->prepare(
                "UPDATE `{$to_ctx['table']}` SET
                    contact_id  = :contact_id,
                    description = :description,
                    `log`       = :log
                WHERE id = :id AND company_id = :company_id"
            )->execute([
                ':contact_id'  => $contact_id,
                ':description' => $description,
                ':log'         => json_encode($to_log),
                ':id'          => $to_id,
                ':company_id'  => $this->company_id,
            ]);

            return;
        }

        $from_warehouse = (int)$data['warehouse_from'];
        $from_zone      = $data['zone_from'];
        $from_aisle     = $data['aisle_from'];
        $from_rack      = $data['rack_from'];
        $to_warehouse   = (int)$data['warehouse_to'];
        $to_zone        = $data['zone_to'];
        $to_aisle       = $data['aisle_to'];
        $to_rack        = $data['rack_to'];

        $source_stock = $whMgmt->getRackStock(
            $from_warehouse, $from_zone, $from_aisle, $from_rack
        );

        if (!$source_stock) {
            throw new Exception("Source rack {$from_zone}-{$from_aisle}-{$from_rack} is empty.");
        }

        if ($source_stock['product_sku'] !== $data['product_sku']) {
            throw new Exception(
                "Source rack holds {$source_stock['product_sku']}, not {$data['product_sku']}."
            );
        }

        if (!empty($data['lot_number']) && $source_stock['lot_number'] !== $data['lot_number']) {
            throw new Exception(
                "Source rack holds lot '{$source_stock['lot_number']}', not '{$data['lot_number']}'."
            );
        }

        if (!empty($data['serial_number']) && $source_stock['serial_number'] !== $data['serial_number']) {
            throw new Exception(
                "Source rack holds serial '{$source_stock['serial_number']}', not '{$data['serial_number']}'."
            );
        }

        $quantity      = (int)$source_stock['in'];
        $lot_number    = $source_stock['lot_number']    ?? null;
        $serial_number = $source_stock['serial_number'] ?? null;

        $from_table = $whMgmt->getStockContext($from_warehouse, 0)['table'];
        $to_table   = $whMgmt->getStockContext($to_warehouse,   0)['table'];
        $table_log  = [$logging];

        $this->pdo->prepare(
            "INSERT INTO `$from_table`
                (uuid, company_id, `date`, product_sku, `out`,
                ref_warehouse, zone, aisle, rack,
                contact_id, `description`, `log`, `type`, lot_number, serial_number)
            VALUES
                (:uuid, :company_id, :date, :product_sku, :quantity,
                :ref_warehouse, :zone, :aisle, :rack,
                :contact_id, :description, :log, 'transfer', :lot_number, :serial_number)"
        )->execute([
            ':uuid'          => $uuid,
            ':company_id'    => $this->company_id,
            ':date'          => date('Y-m-d H:i:s'),
            ':product_sku'   => $data['product_sku'],
            ':quantity'      => $quantity,
            ':ref_warehouse' => $to_warehouse,
            ':zone'          => $from_zone,
            ':aisle'         => $from_aisle,
            ':rack'          => $from_rack,
            ':contact_id'    => $contact_id,
            ':description'   => $description,
            ':log'           => json_encode($table_log),
            ':lot_number'    => $lot_number,
            ':serial_number' => $serial_number,
        ]);
        $from_stock_id = (int)$this->pdo->lastInsertId();

        $this->pdo->prepare(
            "INSERT INTO `$to_table`
                (uuid, company_id, `date`, product_sku, `in`,
                ref_warehouse, ref_id, zone, aisle, rack,
                contact_id, `description`, `log`, `type`, lot_number, serial_number)
            VALUES
                (:uuid, :company_id, :date, :product_sku, :quantity,
                :ref_warehouse, :ref_id, :zone, :aisle, :rack,
                :contact_id, :description, :log, 'transfer', :lot_number, :serial_number)"
        )->execute([
            ':uuid'          => $uuid,
            ':company_id'    => $this->company_id,
            ':date'          => date('Y-m-d H:i:s'),
            ':product_sku'   => $data['product_sku'],
            ':quantity'      => $quantity,
            ':ref_warehouse' => $from_warehouse,
            ':ref_id'        => $from_stock_id,
            ':zone'          => $to_zone,
            ':aisle'         => $to_aisle,
            ':rack'          => $to_rack,
            ':contact_id'    => $contact_id,
            ':description'   => $description,
            ':log'           => json_encode($table_log),
            ':lot_number'    => $lot_number,
            ':serial_number' => $serial_number,
        ]);
        $to_stock_id = (int)$this->pdo->lastInsertId();

        // Back-fill ref_id on from row so both rows point at each other
        $this->pdo->prepare(
            "UPDATE `$from_table` SET ref_id = :ref_id
            WHERE id = :id AND company_id = :company_id"
        )->execute([
            ':ref_id'     => $to_stock_id,
            ':id'         => $from_stock_id,
            ':company_id' => $this->company_id,
        ]);

        $whMgmt->releaseRack($from_warehouse, $from_zone, $from_aisle, $from_rack);
        $whMgmt->occupyRack($to_warehouse, $to_zone, $to_aisle, $to_rack, $data['product_sku'], $to_stock_id);

        $whMgmt->adjustBalance('out', $from_warehouse, $data['product_sku'], 0, $quantity);
        $whMgmt->adjustBalance('in',  $to_warehouse,   $data['product_sku'], 0, $quantity);
    }

}
?>