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

package parser

import (
	"math"
	"os"
	"slices"
	"strings"
	"testing"

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

func mustParse(t *testing.T, path string) *ast.File {
	t.Helper()
	src, err := os.ReadFile(path)
	if err != nil {
		t.Fatalf("read %s: %v", path, err)
	}
	file, errs := Parse(path, string(src))
	if len(errs) > 0 {
		t.Fatalf("parse %s: %v", path, errs)
	}
	return file
}

func texts(f *ast.File) []*ast.Text {
	var out []*ast.Text
	for _, d := range f.Decls {
		if t, ok := d.(*ast.Text); ok {
			out = append(out, t)
		}
	}
	return out
}

// TestNegativeDisplacement is a regression test for a leading negative
// displacement with a base and index: the sign pushed the parenthesis one
// token further out than the lookahead expected, and the whole address used
// to parse empty.
func TestNegativeDisplacement(t *testing.T) {
	f, errs := Parse("neg_amd64.s", `
#include "textflag.h"
TEXT ·f(SB), NOSPLIT, $0
	LEAQ -4(DX)(R9*4), R9
	MOVQ +8(AX), BX
	RET
`)
	if len(errs) > 0 {
		t.Fatalf("parse: %v", errs)
	}
	fn := texts(f)[0]
	var leaq, movq *ast.Instr
	for _, s := range fn.Body {
		if in, ok := s.(*ast.Instr); ok {
			switch in.Mnemonic.Text {
			case "LEAQ":
				leaq = in
			case "MOVQ":
				movq = in
			}
		}
	}
	if leaq == nil || movq == nil {
		t.Fatalf("instructions not parsed: leaq=%v movq=%v", leaq, movq)
	}
	a := leaq.Operands[0].Addr
	if a.Base != "DX" || a.Index != "R9" || a.Scale != 4 || a.Offset != -4 || !a.HasOff {
		t.Errorf("LEAQ addr = %+v, want -4(DX)(R9*4)", a)
	}
	b := movq.Operands[0].Addr
	if b.Base != "AX" || b.Offset != 8 || !b.HasOff {
		t.Errorf("MOVQ addr = %+v, want +8(AX)", b)
	}
}

func TestParseSample(t *testing.T) {
	f := mustParse(t, "../testdata/sample_amd64.s")

	// Includes, GLOBL/DATA and two TEXT functions.
	var includes, globls, datas int
	for _, d := range f.Decls {
		switch d.(type) {
		case *ast.Include:
			includes++
		case *ast.Globl:
			globls++
		case *ast.Data:
			datas++
		}
	}
	if includes != 1 {
		t.Errorf("includes = %d, want 1", includes)
	}
	if globls != 2 {
		t.Errorf("globls = %d, want 2", globls)
	}
	if datas != 4 {
		t.Errorf("datas = %d, want 4", datas)
	}

	txts := texts(f)
	if len(txts) != 2 {
		t.Fatalf("text functions = %d, want 2", len(txts))
	}

	fn := txts[0]
	if fn.Name.Name != "analyzeO1RangeAVX2" {
		t.Errorf("name = %q, want analyzeO1RangeAVX2", fn.Name.Name)
	}
	if fn.Name.Pseudo != "SB" {
		t.Errorf("pseudo = %q, want SB", fn.Name.Pseudo)
	}
	if len(fn.Flags) != 1 || fn.Flags[0] != "NOSPLIT" {
		t.Errorf("flags = %v, want [NOSPLIT]", fn.Flags)
	}
	if fn.Frame == nil || !fn.Frame.Imm.HasVal || fn.Frame.Imm.Val != 0 {
		t.Errorf("frame = %+v, want $0", fn.Frame)
	}
	if fn.Args == nil || fn.Args.Imm.Val != 65 {
		t.Errorf("args = %+v, want 65", fn.Args)
	}
	if fn.Doc == "" {
		t.Error("expected a doc comment on the first TEXT")
	}

	// The body must contain the two labels vec1 and vec1done.
	labels := map[string]bool{}
	for _, s := range fn.Body {
		if l, ok := s.(*ast.Label); ok {
			labels[l.Name.Text] = true
		}
	}
	for _, want := range []string{"vec1", "vec1done"} {
		if !labels[want] {
			t.Errorf("missing label %q", want)
		}
	}
}

func TestOperandStructure(t *testing.T) {
	f := mustParse(t, "../testdata/sample_amd64.s")
	fn := texts(f)[0]

	// Index instructions by mnemonic for targeted checks.
	byMnem := map[string]*ast.Instr{}
	for _, s := range fn.Body {
		if in, ok := s.(*ast.Instr); ok {
			byMnem[in.Mnemonic.Text] = in
		}
	}

	// MOVQ swin_base+0(FP), SI; the first MOVQ in the body.
	var mov *ast.Instr
	for _, s := range fn.Body {
		if in, ok := s.(*ast.Instr); ok && in.Mnemonic.Text == "MOVQ" {
			mov = in
			break
		}
	}
	if mov == nil {
		t.Fatal("MOVQ not found")
	}
	src := mov.Operands[0]
	if src.Kind != ast.OpAddr || src.Addr.Sym == nil {
		t.Fatalf("src operand = %+v, want symbol address", src)
	}
	if src.Addr.Sym.Name != "swin_base" || src.Addr.Sym.Pseudo != "FP" || src.Addr.Sym.Offset != 0 {
		t.Errorf("src symbol = %+v, want swin_base+0(FP)", src.Addr.Sym)
	}
	if mov.Operands[1].Addr.Sym.Name != "SI" {
		t.Errorf("dst = %+v, want SI", mov.Operands[1].Addr)
	}

	// LEAQ (SI)(BX*4), R9
	leaq := byMnem["LEAQ"]
	if leaq == nil {
		t.Fatal("LEAQ not found")
	}
	mem := leaq.Operands[0].Addr
	if mem.Base != "SI" || mem.Index != "BX" || mem.Scale != 4 {
		t.Errorf("LEAQ addr = %+v, want base SI index BX scale 4", mem)
	}

	// ANDQ $-8, R10
	andq := byMnem["ANDQ"]
	if andq == nil {
		t.Fatal("ANDQ not found")
	}
	imm := andq.Operands[0]
	if imm.Kind != ast.OpImmediate || !imm.Imm.Neg || imm.Imm.Val != 8 {
		t.Errorf("ANDQ imm = %+v, want -8", imm.Imm)
	}
}

func TestAVX512Operands(t *testing.T) {
	f := mustParse(t, "../testdata/sample_amd64.s")
	fn := texts(f)[1]
	byMnem := map[string]*ast.Instr{}
	for _, s := range fn.Body {
		if in, ok := s.(*ast.Instr); ok {
			byMnem[in.Mnemonic.Text] = in
		}
	}

	// VALIGND $15, Z9, Z0, Z1; four operands.
	val := byMnem["VALIGND"]
	if val == nil {
		t.Fatal("VALIGND not found")
	}
	if len(val.Operands) != 4 {
		t.Errorf("VALIGND operands = %d, want 4", len(val.Operands))
	}
	if val.Operands[0].Kind != ast.OpImmediate || val.Operands[0].Imm.Val != 15 {
		t.Errorf("VALIGND first operand = %+v, want $15", val.Operands[0])
	}

	// VMOVDQU32 Z0, 4(SI)(AX*1)
	vmov := byMnem["VMOVDQU32"]
	if vmov == nil {
		t.Fatal("VMOVDQU32 not found")
	}
	dst := vmov.Operands[len(vmov.Operands)-1].Addr
	if dst.Offset != 4 || dst.Base != "SI" || dst.Index != "AX" || dst.Scale != 1 {
		t.Errorf("VMOVDQU32 dst = %+v, want 4(SI)(AX*1)", dst)
	}

	// KTESTW K1, K1; mask registers parse as bare names.
	kt := byMnem["KTESTW"]
	if kt == nil || len(kt.Operands) != 2 {
		t.Fatalf("KTESTW = %+v, want two operands", kt)
	}
}

func TestDataWidthAndStatic(t *testing.T) {
	f := mustParse(t, "../testdata/sample_amd64.s")
	var datas []*ast.Data
	for _, d := range f.Decls {
		if dd, ok := d.(*ast.Data); ok {
			datas = append(datas, dd)
		}
	}
	if datas[0].Width != 4 {
		t.Errorf("first DATA width = %d, want 4", datas[0].Width)
	}
	if datas[0].Name.Pseudo != "SB" || datas[0].Name.Offset != 0 {
		t.Errorf("first DATA name = %+v, want +0(SB)", datas[0].Name)
	}
	if datas[0].Value.Kind != ast.OpImmediate || datas[0].Value.Imm.Val != 1 {
		t.Errorf("first DATA value = %+v, want $1", datas[0].Value)
	}
	// The mask24<> entries are static.
	if !datas[2].Name.Static {
		t.Errorf("mask24 DATA should be static, got %+v", datas[2].Name)
	}
}

// TestTruncatedFrameDollar is a regression test for a TEXT directive whose
// frame size is missing after the $: the parser used to slice past the end
// of the token slice and panic.  It must report a diagnostic instead.
func TestTruncatedFrameDollar(t *testing.T) {
	for _, src := range []string{
		"TEXT $\n",
		"TEXT \u00b7foo(SB), $\n",
		"TEXT \u00b7foo(SB), NOSPLIT, $\n",
	} {
		var file *ast.File
		func() {
			defer func() {
				if r := recover(); r != nil {
					t.Fatalf("Parse(%q) panicked: %v", src, r)
				}
			}()
			file, _ = Parse("t.s", src)
		}()
		if file == nil {
			t.Fatalf("Parse(%q) returned no file", src)
		}
		if len(file.Decls) != 1 {
			t.Fatalf("Parse(%q) decls = %d, want 1", src, len(file.Decls))
		}
		txt := file.Decls[0].(*ast.Text)
		if txt.Frame != nil {
			t.Errorf("Parse(%q) frame = %v, want nil", src, txt.Frame)
		}
	}
}

// TestFrameAndArgs parses a well-formed TEXT header and checks that the
// frame and args operands are picked up.
func TestFrameAndArgs(t *testing.T) {
	file, errs := Parse("t.s", "TEXT \u00b7foo(SB), $32-16\n\tRET\n")
	if len(errs) > 0 {
		t.Fatalf("parse errors: %v", errs)
	}
	txt := file.Decls[0].(*ast.Text)
	if txt.Frame == nil || !txt.Frame.Imm.HasVal || txt.Frame.Imm.Val != 32 {
		t.Errorf("frame = %+v, want $32", txt.Frame)
	}
	if txt.Args == nil || !txt.Args.Imm.HasVal || txt.Args.Imm.Val != 16 {
		t.Errorf("args = %+v, want -16", txt.Args)
	}
}

// TestSignedZeroFrame covers the Go runtime's "$-0-24" spelling: a zero
// frame with an explicit sign plus the argument area.
func TestSignedZeroFrame(t *testing.T) {
	file, errs := Parse("t.s", "TEXT \u00b7foo<ABIInternal>(SB), NOSPLIT, $-0-24\n\tRET\n")
	if len(errs) > 0 {
		t.Fatalf("parse errors: %v", errs)
	}
	txt := file.Decls[0].(*ast.Text)
	if txt.Frame == nil || !txt.Frame.Imm.HasVal || txt.Frame.Imm.Val != 0 {
		t.Errorf("frame = %+v, want $-0", txt.Frame)
	}
	if txt.Args == nil || !txt.Args.Imm.HasVal || txt.Args.Imm.Val != 24 {
		t.Errorf("args = %+v, want -24", txt.Args)
	}
	// The <ABIInternal> marker belongs to the symbol: the pseudo-register is
	// consumed, the marker is recorded, and neither leaks into the flags.
	if txt.Name.Pseudo != "SB" {
		t.Errorf("pseudo = %q, want SB", txt.Name.Pseudo)
	}
	if txt.Name.ABI != "ABIInternal" {
		t.Errorf("ABI = %q, want ABIInternal", txt.Name.ABI)
	}
	if !strings.Contains(txt.Name.Raw, "<ABIInternal>") {
		t.Errorf("Raw = %q, want it to contain <ABIInternal>", txt.Name.Raw)
	}
	if want := []string{"NOSPLIT"}; !slices.Equal(txt.Flags, want) {
		t.Errorf("flags = %v, want %v", txt.Flags, want)
	}
}

// TestPipedFlags covers TEXT and GLOBL flag lists joined by '|': the bars are
// their own token kind, skipped by the flag loop, and only the identifiers
// are collected as flags.
func TestPipedFlags(t *testing.T) {
	file, errs := Parse("t.s", "TEXT \u00b7f(SB), NOSPLIT|NOFRAME|DUPOK, $0\n\tRET\n")
	if len(errs) > 0 {
		t.Fatalf("parse errors: %v", errs)
	}
	txt := file.Decls[0].(*ast.Text)
	if want := []string{"NOSPLIT", "NOFRAME", "DUPOK"}; !slices.Equal(txt.Flags, want) {
		t.Errorf("flags = %v, want %v", txt.Flags, want)
	}

	g, errs := Parse("t.s", "GLOBL \u00b7mask(SB), RODATA|NOPTR, $8\n")
	if len(errs) > 0 {
		t.Fatalf("parse errors: %v", errs)
	}
	gl := g.Decls[0].(*ast.Globl)
	if want := []string{"RODATA", "NOPTR"}; !slices.Equal(gl.Flags, want) {
		t.Errorf("flags = %v, want %v", gl.Flags, want)
	}
}

// TestTextMissingSymbolKeepsDecl covers a TEXT with no symbol at all: the
// decl must stay in the tree with a non-nil placeholder name, because the
// linter and the LSP dereference Name on every parsed TEXT.
func TestTextMissingSymbolKeepsDecl(t *testing.T) {
	file, errs := Parse("t.s", "// func f(a int) int\nTEXT $0\n\tMOVQ AX, BX\n")
	if len(errs) == 0 {
		t.Fatal("expected a diagnostic for the missing symbol")
	}
	if file == nil || len(file.Decls) != 1 {
		t.Fatalf("file = %v, want the TEXT decl kept", file)
	}
	txt := file.Decls[0].(*ast.Text)
	if txt.Name == nil {
		t.Fatal("Name must never be nil: downstream tools dereference it")
	}
	if txt.Name.Name == "" {
		t.Error("placeholder name is empty")
	}
	if txt.Frame == nil || !txt.Frame.Imm.HasVal || txt.Frame.Imm.Val != 0 {
		t.Errorf("frame = %+v, want $0", txt.Frame)
	}
	if len(txt.Body) != 1 {
		t.Errorf("body = %d statements, want 1", len(txt.Body))
	}
}

// TestInt64MinimumImmediate covers $-0x8000000000000000: the digits overflow
// int64 when parsed directly, but the negated magnitude is exactly the int64
// minimum and must land in Val rather than the float fallback.
func TestInt64MinimumImmediate(t *testing.T) {
	file, errs := Parse("t.s", "TEXT \u00b7f(SB), $0\n\tMOVQ $-0x8000000000000000, AX\n\tRET\n")
	if len(errs) > 0 {
		t.Fatalf("parse errors: %v", errs)
	}
	txt := file.Decls[0].(*ast.Text)
	instr := txt.Body[0].(*ast.Instr)
	imm := instr.Operands[0].Imm
	if !imm.HasVal || imm.Val != math.MinInt64 {
		t.Errorf("imm = %+v, want Val = %d with HasVal set", imm, math.MinInt64)
	}
	if imm.Float != "" {
		t.Errorf("imm.Float = %q, want empty", imm.Float)
	}
}