package page_test

import (
	"database/sql"
	"os"
	"reflect"

	"errors"
	"testing"

	_ "github.com/lib/pq"
	_ "github.com/mattn/go-sqlite3"
	"github.com/stephenafamo/bob"
	"github.com/stephenafamo/bob/dialect/mysql"
	md "github.com/stephenafamo/bob/dialect/mysql/dialect"
	mm "github.com/stephenafamo/bob/dialect/mysql/sm"
	"github.com/stephenafamo/bob/dialect/psql"
	pd "github.com/stephenafamo/bob/dialect/psql/dialect"
	pm "github.com/stephenafamo/bob/dialect/psql/sm"
	"github.com/stephenafamo/bob/dialect/sqlite"
	sd "github.com/stephenafamo/bob/dialect/sqlite/dialect"
	"github.com/stephenafamo/bob/dialect/sqlite/sm"
	"github.com/stephenafamo/bob/expr"
	"github.com/stephenafamo/scan"
	"go.auvem.com/corestack/page"
)

type item struct {
	ID    int64
	Score int64
}

func itemSort() page.Sort {
	return page.Sort{ID: "items/score/v1", Columns: []page.Column{
		{Expression: expr.Quote("score"), Direction: page.Desc},
		{Expression: expr.Quote("id"), Direction: page.Asc, Unique: true},
	}}
}

func itemKey(i item) []any { return []any{i.Score, i.ID} }

func TestSQLiteFlow(t *testing.T) {
	db, err := bob.Open("sqlite3", ":memory:")
	if err != nil {
		t.Fatal(err)
	}
	defer db.Close()
	databaseFlow(t, db, false)
}

func TestPostgresFlow(t *testing.T) {
	dsn := os.Getenv("PAGE_POSTGRES_DSN")
	if dsn == "" {
		if os.Getenv("PAGE_REQUIRE_POSTGRES") != "" {
			t.Fatal("PAGE_POSTGRES_DSN is required")
		}
		t.Skip("set PAGE_POSTGRES_DSN to run PostgreSQL integration")
	}
	db, err := bob.Open("postgres", dsn)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Close()
	databaseFlow(t, db, true)
}

func databaseFlow(t *testing.T, db bob.DB, postgres bool) {
	t.Helper()
	db.SetMaxOpenConns(1)
	for _, statement := range []string{
		"CREATE TEMP TABLE items (id BIGINT PRIMARY KEY, score BIGINT NOT NULL, tenant BIGINT NOT NULL)",
		"INSERT INTO items VALUES (1,30,1),(2,30,1),(3,20,1),(4,10,1),(5,5,2),(6,30,2)",
	} {
		if _, err := db.ExecContext(t.Context(), statement); err != nil {
			t.Fatal(err)
		}
	}
	fetch := func(direction page.Direction, size int, cursor string) page.Page[item] {
		t.Helper()
		p, err := page.Prepare(itemSort(), itemKey, page.Request{Direction: direction, Size: size, Cursor: cursor}, page.Limits{Default: 2, Maximum: 3})
		if err != nil {
			t.Fatal(err)
		}
		var q bob.Query
		if postgres {
			query := psql.Select(pm.Columns("id", "score"), pm.From("items"), pm.Where(psql.Quote("tenant").EQ(psql.Arg(int64(1)))))
			query.Apply(page.Mod[*pd.SelectQuery](p))
			query.Apply(pm.Where(psql.Quote("score").GT(psql.Arg(int64(0)))))
			q = query
		} else {
			query := sqlite.Select(sm.Columns("id", "score"), sm.From("items"), sm.Where(sqlite.Quote("tenant").EQ(sqlite.Arg(int64(1)))))
			query.Apply(page.Mod[*sd.SelectQuery](p))
			query.Apply(sm.Where(sqlite.Quote("score").GT(sqlite.Arg(int64(0)))))
			q = query
		}
		rows, err := bob.All(t.Context(), db, q, scan.StructMapper[item]())
		if err != nil {
			t.Fatal(err)
		}
		before := append([]item(nil), rows...)
		result, err := p.Page(rows)
		if err != nil {
			t.Fatal(err)
		}
		if !reflect.DeepEqual(before, rows) {
			t.Fatal("Page mutated fetched slice")
		}
		return result
	}
	check := func(got page.Page[item], ids []int64, next, previous bool) {
		t.Helper()
		actual := make([]int64, len(got.Items))
		for i, row := range got.Items {
			actual[i] = row.ID
		}
		if !reflect.DeepEqual(actual, ids) || got.HasNext != next || got.HasPrevious != previous {
			t.Fatalf("got IDs %v next=%v previous=%v; want %v %v %v", actual, got.HasNext, got.HasPrevious, ids, next, previous)
		}
		if len(ids) == 0 && (got.StartCursor != "" || got.EndCursor != "") {
			t.Fatal("empty page has cursors")
		}
		if len(ids) > 0 && (got.StartCursor == "" || got.EndCursor == "") {
			t.Fatal("missing cursors")
		}
	}
	first := fetch(page.Forward, 2, "")
	check(first, []int64{1, 2}, true, false)
	second := fetch(page.Forward, 2, first.EndCursor)
	check(second, []int64{3, 4}, false, true)
	check(fetch(page.Forward, 2, second.EndCursor), []int64{}, false, true)
	last := fetch(page.Backward, 2, "")
	check(last, []int64{3, 4}, false, true)
	previous := fetch(page.Backward, 2, last.StartCursor)
	check(previous, []int64{1, 2}, true, false)
	check(fetch(page.Backward, 2, previous.StartCursor), []int64{}, true, false)
	check(fetch(page.Forward, 0, ""), []int64{1, 2}, true, false)
	check(fetch(page.Forward, 1000, ""), []int64{1, 2, 3}, true, false)
	// A cursor describes a value boundary even after its row is deleted.
	if _, err := db.ExecContext(t.Context(), "DELETE FROM items WHERE id=2"); err != nil {
		t.Fatal(err)
	}
	check(fetch(page.Forward, 2, first.EndCursor), []int64{3, 4}, false, true)
	var countQuery, emptyQuery bob.Query
	if postgres {
		countQuery = psql.Select(pm.Columns("count(*)"), pm.From("items"), pm.Where(psql.Quote("tenant").EQ(psql.Arg(1))))
		emptyQuery = psql.Select(pm.Columns("id"), pm.From("items"), pm.Where(psql.Quote("id").LT(psql.Arg(0))))
	} else {
		countQuery = sqlite.Select(sm.Columns("count(*)"), sm.From("items"), sm.Where(sqlite.Quote("tenant").EQ(sqlite.Arg(1))))
		emptyQuery = sqlite.Select(sm.Columns("id"), sm.From("items"), sm.Where(sqlite.Quote("id").LT(sqlite.Arg(0))))
	}
	count, err := page.Count(t.Context(), db, countQuery)
	if err != nil || count != 3 {
		t.Fatalf("count %d: %v", count, err)
	}
	if _, err := page.Count(t.Context(), db, emptyQuery); !errors.Is(err, sql.ErrNoRows) {
		t.Fatalf("count error lost cause: %v", err)
	}
	_, err = page.Prepare(itemSort(), itemKey, page.Request{Cursor: "not!base64"}, page.Limits{Default: 2, Maximum: 3})
	var cursorError *page.CursorError
	if !errors.As(err, &cursorError) {
		t.Fatalf("invalid cursor: %v", err)
	}
	bad, err := page.Prepare(itemSort(), func(item) []any { return []any{int64(1)} }, page.Request{}, page.Limits{Default: 2, Maximum: 3})
	if err != nil {
		t.Fatal(err)
	}
	result, err := bad.Page([]item{{ID: 1}})
	var keyError *page.KeyError
	if !errors.As(err, &keyError) || !reflect.DeepEqual(result, page.Page[item]{}) {
		t.Fatalf("key failure: %+v %v", result, err)
	}
	if _, err := db.ExecContext(t.Context(), "DELETE FROM items"); err != nil {
		t.Fatal(err)
	}
	check(fetch(page.Forward, 2, ""), []int64{}, false, false)
	check(fetch(page.Backward, 2, ""), []int64{}, false, false)
	check(fetch(page.Forward, 2, first.EndCursor), []int64{}, false, true)
	check(fetch(page.Backward, 2, last.StartCursor), []int64{}, true, false)
}

func TestMySQLModComposition(t *testing.T) {
	p, err := page.Prepare(itemSort(), itemKey, page.Request{}, page.Limits{Default: 2, Maximum: 3})
	if err != nil {
		t.Fatal(err)
	}
	q := mysql.Select(mm.Columns("id", "score"), mm.From("items"), page.Mod[*md.SelectQuery](p))
	q.Apply(mm.Where(mysql.Quote("tenant").EQ(mysql.Arg(int64(1)))))
	// Compile-time composition only; MySQL runtime behavior needs a database test.
}