package lagoon

import (
	"context"
	"fmt"
	"reflect"
	"strings"
	"testing"

	"gorm.io/gorm"
)

func TestOrderClauseAllowList(t *testing.T) {
	allowed := []string{"acme_blog_posts.title", "items.title"}

	got, err := orderClause("acme_blog_posts.title", "asc", allowed, orderOptions{})
	if err != nil {
		t.Fatal(err)
	}
	if got != "acme_blog_posts.title ASC" {
		t.Fatalf("got %q", got)
	}
	if strings.Contains(strings.ToLower(got), "collate") {
		t.Fatalf("must not emit COLLATE: %q", got)
	}

	got, err = orderClause("items.title", "DESC", allowed, orderOptions{})
	if err != nil {
		t.Fatal(err)
	}
	if got != "items.title DESC" {
		t.Fatalf("got %q", got)
	}
	if strings.Contains(strings.ToLower(got), "collate") {
		t.Fatalf("must not emit COLLATE: %q", got)
	}

	if _, err := orderClause("acme_blog_posts.title;drop table x", "asc", allowed, orderOptions{}); err == nil {
		t.Fatal("want reject unknown column")
	}
	if _, err := orderClause("acme_blog_posts.title", "ascending", allowed, orderOptions{}); err == nil {
		t.Fatal("want reject unknown direction")
	}
	if _, err := OrderBy(nil, "items.title", "asc", allowed); err == nil {
		t.Fatal("want nil db error")
	}
	if _, err := orderClause("items.title", "asc", nil, orderOptions{}); err == nil {
		t.Fatal("empty allow-list must reject")
	}
}

func TestOrderClauseCollation(t *testing.T) {
	allowed := []string{"items.title"}
	opts := resolveOrderOptions([]OrderOption{Collate("pl-x-icu")})

	got, err := orderClause("items.title", "asc", allowed, opts)
	if err != nil {
		t.Fatal(err)
	}
	if got != `items.title COLLATE "pl-x-icu" ASC` {
		t.Fatalf("got %q", got)
	}
	got, err = orderClause("items.title", "DESC", allowed, opts)
	if err != nil {
		t.Fatal(err)
	}
	if got != `items.title COLLATE "pl-x-icu" DESC` {
		t.Fatalf("got %q", got)
	}
}

func TestCollateAcceptsValidNames(t *testing.T) {
	allowed := []string{"items.title"}
	for _, name := range []string{
		"pl-x-icu",
		"und-x-icu",
		"en-US-x-icu",
		"C",
		"POSIX",
		"ucs_basic",
		"default",
		"sr_RS.utf8@latin",
		strings.Repeat("a", 63),
	} {
		got, err := orderClause("items.title", "asc", allowed, resolveOrderOptions([]OrderOption{Collate(name)}))
		if err != nil {
			t.Fatalf("%q: %v", name, err)
		}
		want := `items.title COLLATE "` + name + `" ASC`
		if got != want {
			t.Fatalf("%q: got %q want %q", name, got, want)
		}
	}
}

func TestCollateRejectsInvalidNames(t *testing.T) {
	allowed := []string{"items.title"}
	db := &gorm.DB{}
	for _, name := range []string{
		"",
		strings.Repeat("a", 64),
		"pl x icu",
		`pl-x-icu"`,
		`pl-x-icu" ASC, (SELECT 1) --`,
		"pl;DROP TABLE x",
		`pl\x-icu`,
		"pl\x00x-icu",
		"pł-x-icu",
		"-pl-x-icu",
		".pl-x-icu",
	} {
		want := fmt.Sprintf("lagoon: order collation %q is not a valid collation name", name)
		_, err := orderClause("items.title", "asc", allowed, resolveOrderOptions([]OrderOption{Collate(name)}))
		if err == nil || err.Error() != want {
			t.Fatalf("%q: got %v want %s", name, err, want)
		}
		q, err := OrderBy(db, "items.title", "asc", allowed, Collate(name))
		if q != nil || err == nil || err.Error() != want {
			t.Fatalf("OrderBy %q: got (%v, %v)", name, q, err)
		}
	}
	if db.Statement != nil {
		t.Fatal("rejected collation must not touch the GORM handle")
	}
}

func TestCollateOptionOrdering(t *testing.T) {
	allowed := []string{"items.title"}

	got, err := orderClause("items.title", "asc", allowed, resolveOrderOptions([]OrderOption{Collate("C"), Collate("pl-x-icu")}))
	if err != nil {
		t.Fatal(err)
	}
	if got != `items.title COLLATE "pl-x-icu" ASC` {
		t.Fatalf("last Collate must win: %q", got)
	}

	got, err = orderClause("items.title", "asc", allowed, resolveOrderOptions(nil))
	if err != nil {
		t.Fatal(err)
	}
	if got != "items.title ASC" {
		t.Fatalf("no options must keep the plain clause: %q", got)
	}

	// Column and direction are checked before the collation.
	bad := resolveOrderOptions([]OrderOption{Collate(`bad"name`)})
	_, err = orderClause("items.other", "asc", allowed, bad)
	if err == nil || !strings.Contains(err.Error(), "order column") {
		t.Fatalf("column check must run first: %v", err)
	}
	_, err = orderClause("items.title", "sideways", allowed, bad)
	if err == nil || !strings.Contains(err.Error(), "order direction") {
		t.Fatalf("direction check must run second: %v", err)
	}
}

func TestCollatePolishOrderOnLibcDatabase(t *testing.T) {
	admin := lagoonDB(t)
	ctx := t.Context()
	const name = "lagoon_collate_libc"
	if _, err := admin.ExecContext(ctx, `CREATE DATABASE `+name+` TEMPLATE template0 ENCODING 'UTF8' LOCALE_PROVIDER libc LOCALE 'C'`); err != nil && !strings.Contains(err.Error(), "already exists") {
		t.Fatalf("create libc database: %v", err)
	}
	dsn, err := dsnWithDB(lagoonDSN, name)
	if err != nil {
		t.Fatal(err)
	}
	sqlDB, gdb, err := Open(ctx, dsn)
	if err != nil {
		t.Fatalf("Open must accept a libc 'C' database: %v", err)
	}
	t.Cleanup(func() {
		_ = sqlDB.Close()
		_, _ = admin.ExecContext(context.Background(), `DROP DATABASE IF EXISTS `+name+` WITH (FORCE)`)
	})
	if _, err := Use(ctx, sqlDB); err != nil {
		t.Fatalf("Use must accept a libc 'C' database: %v", err)
	}
	if _, err := sqlDB.ExecContext(ctx, `CREATE TABLE words (name text)`); err != nil {
		t.Fatal(err)
	}
	if _, err := sqlDB.ExecContext(ctx, `INSERT INTO words (name) VALUES ('Zebra'), ('Łoś'), ('Lis'), ('Mysz')`); err != nil {
		t.Fatal(err)
	}
	allowed := []string{"words.name"}
	scan := func(opts ...OrderOption) ([]string, error) {
		q, err := OrderBy(gdb.Table("words"), "words.name", "asc", allowed, opts...)
		if err != nil {
			return nil, err
		}
		var names []string
		if err := q.Pluck("name", &names).Error; err != nil {
			return nil, err
		}
		return names, nil
	}

	plain, err := scan()
	if err != nil {
		t.Fatal(err)
	}
	if want := []string{"Lis", "Mysz", "Zebra", "Łoś"}; !reflect.DeepEqual(plain, want) {
		t.Fatalf("plain order on libc 'C': got %v want %v", plain, want)
	}

	polish, err := scan(Collate("pl-x-icu"))
	if err != nil {
		t.Fatal(err)
	}
	if want := []string{"Lis", "Łoś", "Mysz", "Zebra"}; !reflect.DeepEqual(polish, want) {
		t.Fatalf("pl-x-icu order: got %v want %v", polish, want)
	}

	_, err = scan(Collate("no-such-collation-x"))
	if err == nil || !strings.Contains(err.Error(), "no-such-collation-x") {
		t.Fatalf("unknown collation must reach Postgres as an identifier: %v", err)
	}
}