package com.nanri.aiimage.config;

import org.junit.jupiter.api.Test;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;
import java.util.stream.Stream;

import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertTrue;

/**
 * 任务 116：索引迁移 V{N+1}（审计清单落地）。
 * 迁移文件存在且版本续接；按 115 审计清单追加 (module_type, job_type, task_id) 索引；
 * 含验证 SQL、锁表风险标注、回滚步骤；不改历史迁移。
 */
class IndexMigrationV101Test {

    private static final Path DB_DIR = Paths.get("src", "main", "resources", "db");
    private static final Path MIGRATION = DB_DIR.resolve("V101__task_file_job_module_type_task_index.sql");
    private static final Path AUDIT = Paths.get("src", "main", "resources", "..", "..", "..",
            "docs", "explain-index-audit.md").normalize();

    private static String read(Path path) throws IOException {
        return new String(Files.readAllBytes(path), StandardCharsets.UTF_8);
    }

    private static List<Path> allMigrations() throws IOException {
        try (Stream<Path> stream = Files.list(DB_DIR)) {
            return stream.filter(p -> p.getFileName().toString().matches("V\\d+__.*\\.sql"))
                    .sorted()
                    .toList();
        }
    }

    private static int versionOf(Path path) {
        String name = path.getFileName().toString();
        return Integer.parseInt(name.substring(1, name.indexOf('_')));
    }

    @Test
    void test_migration_file_exists() {
        assertTrue(Files.isRegularFile(MIGRATION), "迁移文件必须存在: " + MIGRATION);
    }

    @Test
    void test_migration_version_sequential() throws Exception {
        List<Path> all = allMigrations();
        assertTrue(!all.isEmpty(), "存在迁移文件");
        int maxVersion = all.stream().mapToInt(IndexMigrationV101Test::versionOf).max().orElse(0);
        assertTrue(maxVersion >= 100, "现有迁移最大版本 >= V100: " + maxVersion);
        assertTrue(versionOf(MIGRATION) == 101, "新迁移版本号 V101 续接 V100 之后");
    }

    @Test
    void test_migration_index_created() throws Exception {
        String sql = read(MIGRATION);
        assertTrue(sql.contains("biz_task_file_job"), "迁移作用于 biz_task_file_job");
        assertTrue(sql.contains("idx_file_job_module_type_task"), "索引名与审计清单一致");
        assertTrue(sql.contains("module_type") && sql.contains("job_type") && sql.contains("task_id"),
                "索引列为 (module_type, job_type, task_id)");
        assertTrue(sql.contains("ADD INDEX"), "使用 ADD INDEX");
    }

    @Test
    void test_migration_conditional_repeatable() throws Exception {
        String sql = read(MIGRATION);
        assertTrue(sql.contains("information_schema.STATISTICS"), "通过 information_schema 判存在");
        assertTrue(sql.contains("INDEX_NAME"), "按索引名判断");
        assertTrue(sql.contains("PREPARE") && sql.contains("EXECUTE"), "条件执行（幂等，可重复运行）");
    }

    @Test
    void test_migration_validated() throws Exception {
        String sql = read(MIGRATION);
        assertTrue(sql.contains("SELECT 1"), "验证 SQL（幂等分支）");
        String audit = read(AUDIT);
        assertTrue(audit.contains("idx_file_job_module_type_task"), "审计清单已列出该索引");
        assertTrue(audit.contains("收益") && audit.contains("风险"), "审计清单含收益/风险");
    }

    @Test
    void test_explain_improved() throws Exception {
        String audit = read(AUDIT);
        assertTrue(audit.contains("findAssembleJobsByTaskIds"), "审计覆盖 progress/light Job 查询");
        assertTrue(audit.contains("执行后重跑") || audit.contains("前后计划")
                        || audit.contains("对比"), "审计含迁移前后 EXPLAIN 对比步骤");
    }

    @Test
    void test_migration_no_alter_legacy() throws Exception {
        List<Path> all = allMigrations();
        List<Path> others = all.stream()
                .filter(p -> versionOf(p) != 101)
                .toList();
        for (Path legacy : others) {
            String content = read(legacy);
            assertFalse(content.contains("idx_file_job_module_type_task"),
                    "历史迁移不得包含新索引: " + legacy.getFileName());
        }
    }

    @Test
    void test_migration_rollback_doc() throws Exception {
        String sql = read(MIGRATION);
        assertTrue(sql.contains("DROP INDEX") || sql.contains("drop index"),
                "迁移文件含回滚语句（DROP INDEX idx_file_job_module_type_task）");
        String audit = read(AUDIT);
        assertTrue(audit.contains("回滚") || audit.contains("DROP"),
                "审计文档含回滚步骤说明");
    }

    @Test
    void test_migration_lock_window() throws Exception {
        String sql = read(MIGRATION);
        assertTrue(sql.contains("LOCK") || sql.contains("低峰") || sql.contains("lock")
                        || sql.contains("窗口"), "迁移标注锁表风险/窗口");
    }

    @Test
    void test_migration_backward_safe() throws Exception {
        String sql = read(MIGRATION);
        assertTrue(sql.contains("ALTER TABLE"), "普通 BTREE 索引（不重建表、不删列）");
        assertFalse(sql.contains("DROP COLUMN"), "不删列");
        assertFalse(sql.contains("RENAME"), "不重命名");
        assertTrue(sql.contains("ADD INDEX"), "仅追加索引，向后兼容");
    }
}