<?php

namespace App\Database\Migrations;

use CodeIgniter\Database\Migration;

class CreateInvoiceLines extends Migration
{
    public function up()
    {
        if (!$this->db->tableExists('invoice_lines')) {
            $this->forge->addField([
                'id' => [
                    'type' => 'INT',
                    'constraint' => 11,
                    'unsigned' => true,
                    'auto_increment' => true,
                ],
                'invoice_id' => [
                    'type' => 'INT',
                    'constraint' => 11,
                    'unsigned' => true,
                    'null' => false,
                ],
                'school_year' => [
                    'type' => 'VARCHAR',
                    'constraint' => 9,
                    'null' => false,
                ],
                'line_type' => [
                    'type' => 'VARCHAR',
                    'constraint' => 50,
                    'null' => false,
                ],
                'source_type' => [
                    'type' => 'VARCHAR',
                    'constraint' => 50,
                    'null' => true,
                ],
                'source_id' => [
                    'type' => 'INT',
                    'constraint' => 11,
                    'unsigned' => true,
                    'null' => true,
                ],
                'active_source_key' => [
                    'type' => 'VARCHAR',
                    'constraint' => 120,
                    'null' => true,
                ],
                'description' => [
                    'type' => 'VARCHAR',
                    'constraint' => 255,
                    'null' => false,
                ],
                'quantity' => [
                    'type' => 'DECIMAL',
                    'constraint' => '10,2',
                    'null' => false,
                    'default' => '1.00',
                ],
                'unit_amount_cents' => [
                    'type' => 'INT',
                    'constraint' => 11,
                    'null' => false,
                    'default' => 0,
                ],
                'line_amount_cents' => [
                    'type' => 'INT',
                    'constraint' => 11,
                    'null' => false,
                    'default' => 0,
                ],
                'discount_eligible' => [
                    'type' => 'TINYINT',
                    'constraint' => 1,
                    'null' => false,
                    'default' => 1,
                ],
                'calculation_version' => [
                    'type' => 'VARCHAR',
                    'constraint' => 50,
                    'null' => true,
                ],
                'metadata_json' => [
                    'type' => 'TEXT',
                    'null' => true,
                ],
                'created_at' => [
                    'type' => 'DATETIME',
                    'null' => false,
                ],
                'updated_at' => [
                    'type' => 'DATETIME',
                    'null' => false,
                ],
                'voided_at' => [
                    'type' => 'DATETIME',
                    'null' => true,
                ],
            ]);
            $this->forge->addKey('id', true);
            $this->forge->addKey('invoice_id');
            $this->forge->addKey(['source_type', 'source_id']);
            $this->forge->addUniqueKey('active_source_key', 'uniq_invoice_lines_active_source_key');
            $this->forge->createTable('invoice_lines', true);
        }

        $this->ensureSchoolYearColumn();
        $this->backfillLegacyInvoiceLines();
    }

    public function down()
    {
        if ($this->db->tableExists('invoice_lines')) {
            $this->forge->dropTable('invoice_lines', true);
        }
    }

    private function backfillLegacyInvoiceLines(): void
    {
        if (!$this->db->tableExists('invoices') || !$this->db->tableExists('invoice_lines')) {
            return;
        }

        $existingRows = $this->db->table('invoice_lines')
            ->select('invoice_id')
            ->groupBy('invoice_id')
            ->get()
            ->getResultArray();
        $existing = array_fill_keys(array_map(static fn ($row) => (int) ($row['invoice_id'] ?? 0), $existingRows), true);

        $invoices = $this->db->table('invoices')
            ->select('id, total_amount, invoice_number, school_year, created_at, updated_at')
            ->orderBy('id', 'ASC')
            ->get()
            ->getResultArray();

        $now = date('Y-m-d H:i:s');
        foreach ($invoices as $invoice) {
            $invoiceId = (int) ($invoice['id'] ?? 0);
            if ($invoiceId <= 0 || isset($existing[$invoiceId])) {
                continue;
            }

            $amountCents = (int) round(((float) ($invoice['total_amount'] ?? 0)) * 100);
            $createdAt = $invoice['created_at'] ?? $now;
            $updatedAt = $invoice['updated_at'] ?? $createdAt;

            $this->db->table('invoice_lines')->insert([
                'invoice_id' => $invoiceId,
                'school_year' => (string)($invoice['school_year'] ?? ''),
                'line_type' => 'legacy_invoice_total',
                'source_type' => 'legacy_invoice',
                'source_id' => $invoiceId,
                'active_source_key' => null,
                'description' => 'Legacy invoice total preserved from invoice ' . (string) ($invoice['invoice_number'] ?? $invoiceId),
                'quantity' => '1.00',
                'unit_amount_cents' => $amountCents,
                'line_amount_cents' => $amountCents,
                'discount_eligible' => 0,
                'calculation_version' => 'legacy_import',
                'metadata_json' => json_encode([
                    'source' => 'invoices.total_amount',
                    'legacy_discount_eligible_base_cents' => 0,
                    'reconciliation_required' => true,
                ], JSON_UNESCAPED_SLASHES),
                'created_at' => $createdAt ?: $now,
                'updated_at' => $updatedAt ?: $now,
                'voided_at' => null,
            ]);
        }
    }

    private function ensureSchoolYearColumn(): void
    {
        if (!$this->db->tableExists('invoice_lines')) {
            return;
        }

        if (!$this->db->fieldExists('school_year', 'invoice_lines')) {
            $this->forge->addColumn('invoice_lines', [
                'school_year' => [
                    'type' => 'VARCHAR',
                    'constraint' => 9,
                    'null' => true,
                    'after' => 'invoice_id',
                ],
            ]);
        }

        if ($this->db->tableExists('invoices')) {
            $this->db->query(
                "UPDATE invoice_lines il
                 INNER JOIN invoices i ON i.id = il.invoice_id
                    SET il.school_year = i.school_year
                  WHERE il.school_year IS NULL OR TRIM(il.school_year) = ''"
            );
        }

        $this->db->query("ALTER TABLE invoice_lines MODIFY school_year VARCHAR(9) NOT NULL");
    }
}