// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: BSD-3-Clause

package lexer

import (
	"testing"

	"sourcedock.dev/petrbalvin/gasm-devkit/token"
)

// kinds tokenizes src and returns the kind sequence, dropping Newline/EOF.
func kinds(src string) []token.Kind {
	var out []token.Kind
	for _, t := range Tokenize(src) {
		if t.Kind == token.Newline || t.Kind == token.EOF {
			continue
		}
		out = append(out, t.Kind)
	}
	return out
}

// texts tokenizes src and returns the literal text of each significant token.
func texts(src string) []string {
	var out []string
	for _, t := range Tokenize(src) {
		if t.Kind == token.Newline || t.Kind == token.EOF {
			continue
		}
		out = append(out, t.Text)
	}
	return out
}

func eq[T comparable](t *testing.T, got, want []T) {
	t.Helper()
	if len(got) != len(want) {
		t.Fatalf("length mismatch:\n got  %v\n want %v", got, want)
	}
	for i := range got {
		if got[i] != want[i] {
			t.Fatalf("index %d:\n got  %v\n want %v", i, got, want)
		}
	}
}

func TestTextDirective(t *testing.T) {
	eq(t, texts("TEXT ·analyzeO1RangeAVX2(SB), NOSPLIT, $0-65"),
		[]string{"TEXT", "·analyzeO1RangeAVX2", "(", "SB", ")", ",", "NOSPLIT", ",", "$", "0", "-", "65"})
}

func TestDataAndGlobl(t *testing.T) {
	eq(t, texts("GLOBL ·idx16(SB), RODATA, $64"),
		[]string{"GLOBL", "·idx16", "(", "SB", ")", ",", "RODATA", ",", "$", "64"})
	eq(t, texts("DATA ·idx16+0(SB)/4, $1"),
		[]string{"DATA", "·idx16", "+", "0", "(", "SB", ")", "/", "4", ",", "$", "1"})
}

func TestStaticSymbol(t *testing.T) {
	// mask24<> is a file-local symbol; <> must lex as two angle tokens.
	eq(t, texts("GLOBL mask24<>(SB), RODATA, $16"),
		[]string{"GLOBL", "mask24", "<", ">", "(", "SB", ")", ",", "RODATA", ",", "$", "16"})
}

func TestNegativeImmediate(t *testing.T) {
	eq(t, texts("ANDQ $-8, R10"),
		[]string{"ANDQ", "$", "-", "8", ",", "R10"})
}

func TestHexImmediate(t *testing.T) {
	eq(t, texts("DATA mask24<>+0(SB)/4, $0x80020100"),
		[]string{"DATA", "mask24", "<", ">", "+", "0", "(", "SB", ")", "/", "4", ",", "$", "0x80020100"})
}

func TestMemoryAddressing(t *testing.T) {
	eq(t, texts("LEAQ (SI)(BX*4), R9"),
		[]string{"LEAQ", "(", "SI", ")", "(", "BX", "*", "4", ")", ",", "R9"})
	eq(t, texts("VMOVDQU32 Z0, 4(SI)(AX*1)"),
		[]string{"VMOVDQU32", "Z0", ",", "4", "(", "SI", ")", "(", "AX", "*", "1", ")"})
}

func TestLabelAndComment(t *testing.T) {
	eq(t, kinds("vec1:\n\tJMP vec1 // loop"),
		[]token.Kind{token.Ident, token.Colon, token.Ident, token.Ident, token.Comment})
}

func TestAVX512Mnemonics(t *testing.T) {
	eq(t, texts("VFMADD231PD Z14, Z12, Z10"),
		[]string{"VFMADD231PD", "Z14", ",", "Z12", ",", "Z10"})
	eq(t, texts("KTESTW K1, K1"),
		[]string{"KTESTW", "K1", ",", "K1"})
}

func TestArm64Shifts(t *testing.T) {
	eq(t, texts("ADD R0<<2, R1, R2"),
		[]string{"ADD", "R0", "<<", "2", ",", "R1", ",", "R2"})
	eq(t, texts("MOVD R3->4, R5"),
		[]string{"MOVD", "R3", "->", "4", ",", "R5"})
}

func TestInclude(t *testing.T) {
	eq(t, texts(`#include "textflag.h"`),
		[]string{"#", "include", `"textflag.h"`})
}

func TestPositions(t *testing.T) {
	toks := Tokenize("MOVQ AX, BX\nRET")
	// Find RET and check it landed on line 2.
	var ret token.Token
	for _, tok := range toks {
		if tok.Text == "RET" {
			ret = tok
		}
	}
	if ret.Pos.Line != 2 || ret.Pos.Column != 1 {
		t.Fatalf("RET position = %v, want 2:1", ret.Pos)
	}
}

func TestIllegalNeverPanics(t *testing.T) {
	// A stray backtick and NUL-ish garbage must not crash the scanner.
	toks := Tokenize("MOVQ ` , \x01 AX")
	if len(toks) == 0 {
		t.Fatal("expected tokens")
	}
}

func TestBlockComment(t *testing.T) {
	eq(t, kinds("MOVQ /* inline */ AX"),
		[]token.Kind{token.Ident, token.Comment, token.Ident})
	// An unterminated block comment is tolerated.
	toks := Tokenize("MOVQ /* never closed")
	if toks[len(toks)-2].Kind != token.Comment {
		t.Errorf("expected a comment token, got %v", toks)
	}
}

func TestRuneLiteral(t *testing.T) {
	eq(t, texts("MOVL $'a', AX"),
		[]string{"MOVL", "$", "'a'", ",", "AX"})
}

func TestFloatAndBases(t *testing.T) {
	eq(t, texts("$1.5"), []string{"$", "1.5"})
	eq(t, texts("$0b1010"), []string{"$", "0b1010"})
	eq(t, texts("$0o755"), []string{"$", "0o755"})
	eq(t, texts("$1e3"), []string{"$", "1e3"})
}

func TestOperatorVariants(t *testing.T) {
	eq(t, texts("R0>>2"), []string{"R0", ">>", "2"})
	eq(t, texts("@>"), []string{"@", ">"})
	eq(t, texts("a/b"), []string{"a", "/", "b"})
}

// TestPipeFlags covers the '|' that joins TEXT/GLOBL flag lists: it must scan
// as a token of its own so the formatter can preserve the bars the Go
// toolchain requires.
func TestPipeFlags(t *testing.T) {
	eq(t, texts("TEXT ·f(SB), NOSPLIT|NOFRAME|DUPOK, $0"),
		[]string{"TEXT", "·f", "(", "SB", ")", ",", "NOSPLIT", "|", "NOFRAME", "|", "DUPOK", ",", "$", "0"})
}

// TestNulIsIllegal pins the difference between the end of input and a real
// NUL rune: the NUL must surface as an Illegal token and scanning must
// continue past it, so nothing after it is silently dropped.
func TestNulIsIllegal(t *testing.T) {
	eq(t, texts("MOVQ \x00 AX"), []string{"MOVQ", "\x00", "AX"})
}

// TestOffsetsAroundInvalidByte pins Position.Offset against the original
// bytes: an invalid UTF-8 byte decodes to RuneError but advances the offset
// table by exactly one byte, so every later position stays a true byte
// offset.  Columns count runes, so the invalid byte occupies one column like
// any other character.
func TestOffsetsAroundInvalidByte(t *testing.T) {
	// bytes: 'A'=0, ' '=1, 0xff=2, ' '=3, 'B'=4, '\n'=5, 'C'=6.
	toks := Tokenize("A \xff B\nC")
	want := []struct {
		text string
		off  int
	}{
		{"A", 0}, {"\uFFFD", 2}, {"B", 4}, {"\n", 5}, {"C", 6},
	}
	if len(toks) != len(want)+1 || toks[len(toks)-1].Kind != token.EOF {
		t.Fatalf("tokens = %v, want %v plus EOF", toks, want)
	}
	for i, w := range want {
		if toks[i].Text != w.text || toks[i].Pos.Offset != w.off {
			t.Errorf("token %d = %q@%d, want %q@%d", i, toks[i].Text, toks[i].Pos.Offset, w.text, w.off)
		}
	}
	if got := toks[len(toks)-1].Pos.Offset; got != 7 {
		t.Errorf("EOF offset = %d, want 7 (source length)", got)
	}
	if toks[1].Pos.Line != 1 || toks[1].Pos.Column != 3 {
		t.Errorf("invalid byte position = %v, want 1:3", toks[1].Pos)
	}
	if toks[3].Kind != token.Newline || toks[3].Pos.Line != 1 || toks[3].Pos.Column != 6 {
		t.Errorf("newline token = %v, want 1:6", toks[3])
	}
	if toks[4].Pos.Line != 2 || toks[4].Pos.Column != 1 {
		t.Errorf("C position = %v, want 2:1", toks[4].Pos)
	}
}