package format

import (
	"os"
	"path/filepath"
	"strings"
	"testing"

	"github.com/hein/pgtidy/pkg/config"
	"github.com/hein/pgtidy/pkg/lexer"
	"github.com/hein/pgtidy/pkg/parser"
)

func format(src string) string {
	return File(parser.Parse(src), config.Default())
}

func TestFormatHeaderGolden(t *testing.T) {
	src := "--select * from dropall('resolvespec_login');\n" +
		"create or replace function resolvespec_login(\n" +
		"INOUT p_data jsonb, OUT p_success boolean, OUT p_error text)\n" +
		"language plpgsql volatile security definer\n" +
		"as $$\nbegin end;\n$$;\n"

	want := "--select * from dropall('resolvespec_login');\n" +
		"CREATE OR REPLACE FUNCTION resolvespec_login(\n" +
		"   INOUT p_data jsonb\n" +
		"  ,OUT p_success boolean\n" +
		"  ,OUT p_error text\n" +
		")\n" +
		"LANGUAGE plpgsql\n" +
		"VOLATILE\n" +
		"SECURITY DEFINER\n" +
		"AS\n" +
		"$$\nbegin end;\n$$;\n"

	got := format(src)
	if got != want {
		t.Errorf("header format mismatch\n--- got ---\n%s\n--- want ---\n%s", got, want)
	}
}

func TestIdempotentSmall(t *testing.T) {
	src := "create function f(a int,b text) returns void language sql as $$ select 1 $$;"
	once := format(src)
	twice := format(once)
	if once != twice {
		t.Errorf("not idempotent\n--- once ---\n%s\n--- twice ---\n%s", once, twice)
	}
}

func TestCorpusIdempotentAndSafe(t *testing.T) {
	dir := filepath.Join("..", "..", "testdata", "corpus")
	entries, err := os.ReadDir(dir)
	if err != nil {
		t.Skipf("no corpus: %v", err)
	}
	var seen int
	for _, e := range entries {
		if e.IsDir() || !strings.HasSuffix(e.Name(), ".pgsql") {
			continue
		}
		seen++
		data, err := os.ReadFile(filepath.Join(dir, e.Name()))
		if err != nil {
			t.Fatal(err)
		}
		src := string(data)
		once := format(src)
		twice := format(once)
		if once != twice {
			t.Errorf("%s: not idempotent", e.Name())
		}
		if !semanticallyEqual(src, once) {
			t.Errorf("%s: formatting changed semantics", e.Name())
		}
	}
	if seen == 0 {
		t.Skip("no corpus files")
	}
	t.Logf("formatted %d corpus files (idempotent + semantically equal)", seen)
}

// semanticallyEqual compares the non-trivia token streams of two sources,
// treating unquoted identifiers/keywords case-insensitively and everything
// else (strings, numbers, dollar bodies, operators, punctuation) exactly. This
// validates that formatting changed only layout/casing, never meaning.
func semanticallyEqual(a, b string) bool {
	ta := significant(a)
	tb := significant(b)
	if len(ta) != len(tb) {
		return false
	}
	for i := range ta {
		if ta[i].Kind != tb[i].Kind {
			return false
		}
		if ta[i].Kind == lexer.Ident {
			if !strings.EqualFold(ta[i].Text, tb[i].Text) {
				return false
			}
		} else if ta[i].Text != tb[i].Text {
			return false
		}
	}
	return true
}

func significant(src string) []lexer.Token {
	var out []lexer.Token
	for _, t := range lexer.Lex(src) {
		if t.Kind == lexer.EOF || t.IsTrivia() {
			continue
		}
		out = append(out, t)
	}
	return out
}