// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright (C) 2026 Bryan Joshua Pedini

package main

import (
	"context"
	"database/sql"
	"fmt"
	"os"
	"testing"
	"time"

	_ "github.com/go-sql-driver/mysql"
)

// Isolated test schema, per PLAN.md Phase 1: a dedicated table
// (test_pdnsapi_records) on the live MariaDB, never the real coredns_records
// table. TABLE_PREFIX for the Store under test is "test_pdnsapi_".
const testTablePrefix = "test_pdnsapi_"
const testTableName = testTablePrefix + "records"

var (
	testDB       *sql.DB
	testDBReason string // non-empty if the DB is unreachable; tests should t.Skip with this
	testDBReady  bool
)

func TestMain(m *testing.M) {
	dsn := os.Getenv("MYSQL_DSN")
	if dsn == "" {
		dsn = "coredns:coredns@tcp(127.0.0.1:3306)/coredns?parseTime=true"
	}

	db, err := sql.Open("mysql", dsn)
	if err != nil {
		testDBReason = fmt.Sprintf("mysql: sql.Open failed: %v", err)
	} else {
		ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
		pingErr := db.PingContext(ctx)
		cancel()
		if pingErr != nil {
			testDBReason = fmt.Sprintf("mysql: unreachable at %s: %v", dsn, pingErr)
		} else {
			testDB = db
			testDBReady = true
		}
	}

	code := m.Run()

	if testDB != nil {
		// Final safety net teardown in case an individual test's defer was
		// skipped (e.g. t.Fatal before cleanup registration). Never touches
		// coredns_records — only the isolated test_pdnsapi_records table.
		_, _ = testDB.Exec(fmt.Sprintf("DROP TABLE IF EXISTS %s", testTableName))
		testDB.Close()
	}

	os.Exit(code)
}

// requireDB skips the calling test if the live MariaDB is unreachable.
func requireDB(t *testing.T) *sql.DB {
	t.Helper()
	if !testDBReady {
		t.Skipf("skipping: live MySQL/MariaDB not reachable (%s)", testDBReason)
	}
	return testDB
}

// createTestSchema (re)creates test_pdnsapi_records with the exact live
// schema from docs/SEMANTICS.md §1, and registers a cleanup to drop it.
func createTestSchema(t *testing.T) {
	t.Helper()
	db := requireDB(t)

	ctx := context.Background()
	_, err := db.ExecContext(ctx, fmt.Sprintf(`DROP TABLE IF EXISTS %s`, testTableName))
	if err != nil {
		t.Fatalf("drop existing test table: %v", err)
	}

	_, err = db.ExecContext(ctx, fmt.Sprintf(`CREATE TABLE %s (
		id int(11) NOT NULL AUTO_INCREMENT,
		zone varchar(255) NOT NULL,
		name varchar(255) NOT NULL,
		ttl int(11) DEFAULT NULL,
		content text DEFAULT NULL,
		record_type varchar(255) NOT NULL,
		PRIMARY KEY (id)
	) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4`, testTableName))
	if err != nil {
		t.Fatalf("create test table: %v", err)
	}

	t.Cleanup(func() {
		_, err := db.ExecContext(context.Background(), fmt.Sprintf(`DROP TABLE IF EXISTS %s`, testTableName))
		if err != nil {
			t.Errorf("drop test table on cleanup: %v", err)
		}
	})
}

// seedRow is one row to insert during reseed.
type seedRow struct {
	zone       string
	name       string
	ttl        sql.NullInt64
	content    string
	recordType string
}

// exampleComSeed is the SOA/NS/A/CNAME example.com. seed from
// docs/SEMANTICS.md §1 (mirrors the live coredns_records example.com data),
// plus two TXT rows on one name to exercise rrset aggregation.
func exampleComSeed() []seedRow {
	nn := func(v int64) sql.NullInt64 { return sql.NullInt64{Int64: v, Valid: true} }
	return []seedRow{
		{"example.com.", "", nn(300), `{"ttl":300, "mbox":"hostmaster.example.com.", "ns":"ns1.example.com.", "refresh":44, "retry":55, "expire":66}`, "SOA"},
		{"example.com.", "", nn(300), `{"host":"ns1.example.com."}`, "NS"},
		{"example.com.", "", nn(300), `{"ip":"1.2.3.4"}`, "A"},
		{"example.com.", "www", nn(300), `{"host":"example.com."}`, "CNAME"},
		{"example.com.", "multi", nn(120), `{"text":"first"}`, "TXT"},
		{"example.com.", "multi", nn(120), `{"text":"second"}`, "TXT"},
	}
}

// reseed truncates test_pdnsapi_records and inserts the known seed rows.
// Call at the start of every DB-backed test that reads or mutates rows, since
// the table is shared mutable state across tests in the same run.
func reseed(t *testing.T, db *sql.DB, rows []seedRow) {
	t.Helper()
	ctx := context.Background()

	if _, err := db.ExecContext(ctx, fmt.Sprintf("TRUNCATE TABLE %s", testTableName)); err != nil {
		t.Fatalf("truncate test table: %v", err)
	}

	insert := fmt.Sprintf("INSERT INTO %s (zone, name, ttl, content, record_type) VALUES (?, ?, ?, ?, ?)", testTableName)
	for _, row := range rows {
		if _, err := db.ExecContext(ctx, insert, row.zone, row.name, row.ttl, row.content, row.recordType); err != nil {
			t.Fatalf("seed insert %+v: %v", row, err)
		}
	}
}

// --- Store-level tests -------------------------------------------------

func TestStoreListZones(t *testing.T) {
	createTestSchema(t)
	db := requireDB(t)
	reseed(t, db, exampleComSeed())

	st := NewStore(db, testTablePrefix)
	zones, err := st.ListZones(context.Background())
	if err != nil {
		t.Fatal(err)
	}
	if len(zones) != 1 || zones[0] != "example.com." {
		t.Fatalf("zones = %v, want [example.com.]", zones)
	}
}

func TestStoreZoneExists(t *testing.T) {
	createTestSchema(t)
	db := requireDB(t)
	reseed(t, db, exampleComSeed())

	st := NewStore(db, testTablePrefix)
	ok, err := st.ZoneExists(context.Background(), "example.com.")
	if err != nil {
		t.Fatal(err)
	}
	if !ok {
		t.Fatal("expected example.com. to exist")
	}

	ok, err = st.ZoneExists(context.Background(), "nope.com.")
	if err != nil {
		t.Fatal(err)
	}
	if ok {
		t.Fatal("expected nope.com. to not exist")
	}
}

func TestStoreGetZoneRecords(t *testing.T) {
	createTestSchema(t)
	db := requireDB(t)
	reseed(t, db, exampleComSeed())

	st := NewStore(db, testTablePrefix)
	records, err := st.GetZoneRecords(context.Background(), "example.com.")
	if err != nil {
		t.Fatal(err)
	}
	if len(records) != len(exampleComSeed()) {
		t.Fatalf("got %d records, want %d", len(records), len(exampleComSeed()))
	}
}

func TestStoreApplyRRsetsReplace(t *testing.T) {
	createTestSchema(t)
	db := requireDB(t)
	reseed(t, db, exampleComSeed())

	st := NewStore(db, testTablePrefix)
	changes := []RRsetChange{
		{
			Zone:       "example.com.",
			Name:       "www",
			RecordType: "CNAME",
			ChangeType: "REPLACE",
			TTL:        60,
			Contents:   []string{`{"host":"other.example.com."}`},
		},
	}
	if err := st.ApplyRRsets(context.Background(), changes); err != nil {
		t.Fatal(err)
	}

	rows, err := db.QueryContext(context.Background(),
		fmt.Sprintf("SELECT content FROM %s WHERE zone=? AND name=? AND record_type=?", testTableName),
		"example.com.", "www", "CNAME")
	if err != nil {
		t.Fatal(err)
	}
	defer rows.Close()
	var contents []string
	for rows.Next() {
		var c string
		if err := rows.Scan(&c); err != nil {
			t.Fatal(err)
		}
		contents = append(contents, c)
	}
	if err := rows.Err(); err != nil {
		t.Fatal(err)
	}
	if len(contents) != 1 || contents[0] != `{"host":"other.example.com."}` {
		t.Fatalf("contents = %v, want single other.example.com. row", contents)
	}
}

func TestStoreApplyRRsetsDelete(t *testing.T) {
	createTestSchema(t)
	db := requireDB(t)
	reseed(t, db, exampleComSeed())

	st := NewStore(db, testTablePrefix)
	changes := []RRsetChange{
		{Zone: "example.com.", Name: "www", RecordType: "CNAME", ChangeType: "DELETE"},
	}
	if err := st.ApplyRRsets(context.Background(), changes); err != nil {
		t.Fatal(err)
	}

	var count int
	err := db.QueryRowContext(context.Background(),
		fmt.Sprintf("SELECT COUNT(*) FROM %s WHERE zone=? AND name=? AND record_type=?", testTableName),
		"example.com.", "www", "CNAME").Scan(&count)
	if err != nil {
		t.Fatal(err)
	}
	if count != 0 {
		t.Fatalf("count = %d, want 0 after DELETE", count)
	}
}