<?php

/**
 * ContactManager
 *
 * Handles all CRUD and soft-delete operations for contacts and contact types.
 *
 * Method order:
 *   Master file basis  → get/save/delete for contact types and contacts
 *   Transaction basis  → (none — contacts are master data only)
 *   Report basis       → (none — reporting is handled by ReportManager)
 *
 * Note: Write methods do NOT manage their own DB transactions.
 * Callers must wrap multi-step operations inside dbTransaction().
 *
 * Security: All SQL uses PDO prepared statements with bound parameters.
 * No user input is ever interpolated directly into a query string.
 */
class ContactManager {

    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
    // ─────────────────────────────────────────────────────────────

    /**
     * Check whether a contact is referenced by any active stock transaction
     * across all td_stock_* warehouse tables.
     *
     * Used as a pre-delete guard to prevent orphaning stock records.
     * Scans information_schema to discover all td_stock_* tables dynamically.
     * Table names from information_schema are backtick-quoted for safety.
     *
     * @param int $contact_id  The md_contact.id to check.
     * @return bool  true if at least one stock row references this contact, false if clear.
     */
    private function hasActiveStock(int $contact_id): bool {

        $sth = $this->pdo->prepare(
            "SELECT table_name FROM information_schema.tables
             WHERE table_schema = DATABASE()
               AND table_name LIKE 'td_stock_%'"
        );
        $sth->execute();
        $tables = $sth->fetchAll(PDO::FETCH_COLUMN);

        foreach ($tables as $table) {
            // table name comes from information_schema (trusted system table),
            // and is backtick-quoted — no user input reaches the table identifier.
            $sth = $this->pdo->prepare(
                "SELECT COUNT(*) FROM `$table`
                 WHERE company_id = :company_id
                   AND contact_id = :contact_id"
            );
            $sth->execute([
                ':company_id' => $this->company_id,
                ':contact_id' => $contact_id,
            ]);
            if ($sth->fetchColumn() > 0) {
                return true;
            }
        }

        return false;
    }

    /**
     * Build a standard audit log entry array for append-to-JSON log columns.
     *
     * Captures the acting user_id, current datetime, session login time,
     * and a short action label (e.g. 'delete', 'update').
     *
     * Usage:
     *   $log[] = $this->buildLogEntry('delete');
     *   $params[':log'] = json_encode($log);
     *
     * @param string $action  Short label describing the operation (e.g. 'delete').
     * @return array  Associative array ready to be appended to a log array.
     */
    private function buildLogEntry(string $action): array {
        return [
            'user_id' => $_SESSION['login_user_id'] ?? null,
            'dt'      => date('Y-m-d H:i:s'),
            'login'   => isset($_SESSION['otpTime'])
                         ? date('Y-m-d H:i:s', $_SESSION['otpTime'])
                         : null,
            'action'  => $action,
        ];
    }

    // ─────────────────────────────────────────────────────────────
    // MASTER FILE BASIS — Contact Type
    // ─────────────────────────────────────────────────────────────

    /**
     * Return all contact types for the company.
     *
     * Used to populate dropdowns and the contact type listing page.
     *
     * @return array  All rows from md_contact_type for this company.
     */
    public function getContactTypeList(): array
    {
        $sth = $this->pdo->prepare(
            "SELECT * FROM md_contact_type
            WHERE company_id = :company_id"
        );
        $sth->execute([':company_id' => $this->company_id]);
        return $sth->fetchAll(PDO::FETCH_ASSOC);
    }

    /**
     * Fetch a single contact type row by its primary key.
     *
     * Used to pre-fill the edit form on the manage contact type page.
     *
     * @param int $id  The md_contact_type.id to fetch.
     * @return array|false  Associative row, or false if not found.
     */
    public function getContactTypeById(int $id): array|false
    {
        $sth = $this->pdo->prepare(
            "SELECT * FROM md_contact_type
            WHERE company_id = :company_id AND id = :id"
        );
        $sth->execute([':company_id' => $this->company_id, ':id' => $id]);
        return $sth->fetch(PDO::FETCH_ASSOC);
    }

    /**
     * Insert a new contact type or update an existing one.
     *
     * Pass $data['id'] = 0 to insert; pass $data['id'] > 0 to update.
     * The $logging array is appended to the row's JSON log column
     * (caller constructs this from session/request context).
     *
     * Must be called inside dbTransaction() by the caller.
     *
     * @param array $data     Keys: id, contact_type, description, status.
     * @param array $logging  Audit entry to append to the log column.
     */
    public function saveContactType(array $data, array $logging): void
    {
        $id = (int)($data['id'] ?? 0);

        $sth = $this->pdo->prepare(
            "SELECT `log` FROM md_contact_type
            WHERE company_id = :company_id AND id = :id"
        );
        $sth->execute([':company_id' => $this->company_id, ':id' => $id]);
        $table_log   = json_decode($sth->fetchColumn() ?: '[]', true) ?: [];
        $table_log[] = $logging;

        $params = [
            ':company_id'   => $this->company_id,
            ':contact_type' => $data['contact_type'],
            ':description'  => $data['description'],
            ':status'       => (int)$data['status'],
            ':log'          => json_encode($table_log),
        ];

        if ($id > 0) {
            $params[':id'] = $id;
            $this->pdo->prepare(
                "UPDATE md_contact_type SET
                    `contact_type` = :contact_type,
                    `description`  = :description,
                    `status`       = :status,
                    `log`          = :log
                WHERE id = :id AND company_id = :company_id"
            )->execute($params);
        } else {
            $this->pdo->prepare(
                "INSERT INTO md_contact_type
                    (company_id, contact_type, `description`, `status`, `log`)
                VALUES
                    (:company_id, :contact_type, :description, :status, :log)"
            )->execute($params);
        }
    }

    /**
     * Soft-delete a contact type by negating its company_id.
     *
     * Blocks deletion if any md_contact row is still assigned to this type,
     * preventing orphaned contacts.
     *
     * Must be called inside dbTransaction() by the caller.
     *
     * @param int $type_id  The md_contact_type.id to delete.
     * @throws Exception  If the type is not found or has contacts assigned to it.
     */
    public function deleteContactType(int $type_id): void {

        $sth = $this->pdo->prepare(
            "SELECT id, contact_type, `log` FROM md_contact_type
             WHERE company_id = :company_id AND id = :id"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':id'         => $type_id,
        ]);
        $row = $sth->fetch(PDO::FETCH_ASSOC);

        if (!$row) {
            throw new Exception("Contact type not found.");
        }

        // Block if any contact references this type
        $sth = $this->pdo->prepare(
            "SELECT COUNT(*) FROM md_contact
             WHERE company_id = :company_id
               AND contact_type = :type_id"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':type_id'    => $type_id,
        ]);

        if ($sth->fetchColumn() > 0) {
            throw new Exception(
                "Cannot delete — contact type \"{$row['contact_type']}\" " .
                "still has contacts assigned to it."
            );
        }

        // Append delete event to log
        $log   = json_decode($row['log'] ?? '[]', true) ?: [];
        $log[] = $this->buildLogEntry('delete');

        // Soft-delete: negate company_id so row is hidden but recoverable
        $this->pdo->prepare(
            "UPDATE md_contact_type
             SET company_id = company_id * -1,
                 `log`      = :log
             WHERE id = :id AND company_id = :company_id"
        )->execute([
            ':log'        => json_encode($log),
            ':id'         => $type_id,
            ':company_id' => $this->company_id,
        ]);
    }

    // ─────────────────────────────────────────────────────────────
    // MASTER FILE BASIS — Contact
    // ─────────────────────────────────────────────────────────────

    /**
     * Return all contacts for the company.
     *
     * Used to populate the contact listing page and bulk dropdowns.
     *
     * @return array  All rows from md_contact for this company.
     */
    public function getContactList(): array
    {
        $sth = $this->pdo->prepare(
            "SELECT * FROM md_contact
            WHERE company_id = :company_id"
        );
        $sth->execute([':company_id' => $this->company_id]);
        return $sth->fetchAll(PDO::FETCH_ASSOC);
    }

    /**
     * Fetch a single contact row by its primary key.
     *
     * Used to pre-fill the edit form on the manage contact page.
     *
     * @param int $id  The md_contact.id to fetch.
     * @return array|false  Associative row, or false if not found.
     */
    public function getContactById(int $id): array|false
    {
        $sth = $this->pdo->prepare(
            "SELECT * FROM md_contact
            WHERE company_id = :company_id AND id = :id"
        );
        $sth->execute([':company_id' => $this->company_id, ':id' => $id]);
        return $sth->fetch(PDO::FETCH_ASSOC);
    }

    /**
     * Search contacts by name keyword — for live autocomplete on stock forms.
     *
     * Returns up to 50 matches. The keyword is safely bound as a LIKE parameter;
     * no wildcard escaping is needed here since '%' wrapping is the intended behaviour.
     *
     * @param string $keyword  Partial contact name to match.
     * @return array  Matching md_contact rows.
     */
    public function searchContact(string $keyword): array
    {
        $sth = $this->pdo->prepare(
            "SELECT * FROM md_contact
            WHERE company_id = :company_id
            AND contact_name LIKE :keyword
            LIMIT 50"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':keyword'    => '%' . $keyword . '%',
        ]);
        return $sth->fetchAll(PDO::FETCH_ASSOC);
    }

    /**
     * Insert a new contact or update an existing one.
     *
     * Pass $data['id'] = 0 to insert; pass $data['id'] > 0 to update.
     * $contact_image is the resolved filename/path from FileUploader — may be
     * the existing image when no new file was uploaded.
     * The $logging array is appended to the row's JSON log column.
     *
     * Must be called inside dbTransaction() by the caller.
     *
     * @param array  $data           Keys: id, contact_name, tax_id, organization, branch,
     *                               contact_type, billing_address, shipping_location,
     *                               shipping_address, remark, status.
     * @param array  $logging        Audit entry to append to the log column.
     * @param string $contact_image  Stored filename for the contact's profile image.
     */
    public function saveContact(array $data, array $logging, string $contact_image): void
    {
        $id = (int)($data['id'] ?? 0);

        $sth = $this->pdo->prepare(
            "SELECT `log` FROM md_contact
            WHERE company_id = :company_id AND id = :id"
        );
        $sth->execute([':company_id' => $this->company_id, ':id' => $id]);
        $table_log   = json_decode($sth->fetchColumn() ?: '[]', true) ?: [];
        $table_log[] = $logging;

        $params = [
            ':company_id'        => $this->company_id,
            ':contact_name'      => $data['contact_name'],
            ':tax_id'            => $data['tax_id'],
            ':organization'      => $data['organization'],
            ':branch'            => $data['branch'],
            ':contact_type'      => (int)$data['contact_type'],
            ':billing_address'   => $data['billing_address'],
            ':shipping_location' => $data['shipping_location'],
            ':shipping_address'  => $data['shipping_address'],
            ':remark'            => $data['remark'],
            ':contact_image'     => $contact_image,
            ':status'            => (int)$data['status'],
            ':log'               => json_encode($table_log),
        ];

        if ($id > 0) {
            $params[':id'] = $id;
            $this->pdo->prepare(
                "UPDATE md_contact SET
                    `contact_name`       = :contact_name,
                    `tax_id`             = :tax_id,
                    `organization`       = :organization,
                    `branch`             = :branch,
                    `contact_type`       = :contact_type,
                    `billing_address`    = :billing_address,
                    `shipping_location`  = :shipping_location,
                    `shipping_address`   = :shipping_address,
                    `remark`             = :remark,
                    `contact_image`      = :contact_image,
                    `status`             = :status,
                    `log`                = :log
                WHERE id = :id AND company_id = :company_id"
            )->execute($params);
        } else {
            $this->pdo->prepare(
                "INSERT INTO md_contact
                    (company_id, contact_name, tax_id, organization, branch, contact_type,
                    billing_address, shipping_location, shipping_address, remark, contact_image, status, log)
                VALUES
                    (:company_id, :contact_name, :tax_id, :organization, :branch, :contact_type,
                    :billing_address, :shipping_location, :shipping_address, :remark, :contact_image, :status, :log)"
            )->execute($params);
        }
    }

    /**
     * Soft-delete a contact by negating its company_id.
     *
     * Blocks deletion if the contact is referenced in any active stock
     * transaction across all td_stock_* warehouse tables, preventing
     * broken foreign key references in transaction history.
     *
     * Must be called inside dbTransaction() by the caller.
     *
     * @param int $contact_id  The md_contact.id to delete.
     * @throws Exception  If the contact is not found or has active stock references.
     */
    public function deleteContact(int $contact_id): void {

        $sth = $this->pdo->prepare(
            "SELECT id, contact_name, `log` FROM md_contact
             WHERE company_id = :company_id AND id = :id"
        );
        $sth->execute([
            ':company_id' => $this->company_id,
            ':id'         => $contact_id,
        ]);
        $row = $sth->fetch(PDO::FETCH_ASSOC);

        if (!$row) {
            throw new Exception("Contact not found.");
        }

        // Block if contact is referenced in any active stock transaction
        if ($this->hasActiveStock($contact_id)) {
            throw new Exception(
                "Cannot delete — \"{$row['contact_name']}\" " .
                "is referenced in active stock transactions."
            );
        }

        // Append delete event to log
        $log   = json_decode($row['log'] ?? '[]', true) ?: [];
        $log[] = $this->buildLogEntry('delete');

        // Soft-delete: negate company_id so row is hidden but recoverable
        $this->pdo->prepare(
            "UPDATE md_contact
             SET company_id = company_id * -1,
                 `log`      = :log
             WHERE id = :id AND company_id = :company_id"
        )->execute([
            ':log'        => json_encode($log),
            ':id'         => $contact_id,
            ':company_id' => $this->company_id,
        ]);
    }
}