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

//go:build linux && riscv64

package debug

import (
	"fmt"
	"strings"

	"sourcedock.dev/petrbalvin/gasm-devkit/arch"
	"sourcedock.dev/petrbalvin/gasm-devkit/disasm"
)

// Disassemble decodes the instruction at the given address in the debuggee's
// memory and returns its text representation and length in bytes.
func (s *Session) Disassemble(addr uint64) (string, int, error) {
	mem, err := s.ReadMemory(addr, 4)
	if err != nil {
		return "", 0, err
	}
	ins, err := disasm.Decode(arch.RISCV, mem, addr)
	if err != nil {
		return "", 0, err
	}
	return ins.Text, ins.Len, nil
}

// DisassembleN decodes up to n instructions starting at addr.
func (s *Session) DisassembleN(addr uint64, n int) string {
	var result string
	pc := addr
	for range n {
		text, length, err := s.Disassemble(pc)
		if err != nil {
			result += fmt.Sprintf("  %#08x: <error: %v>\n", pc, err)
			break
		}
		result += fmt.Sprintf("  %#08x: %s\n", pc, text)
		if length == 0 {
			length = 4
		}
		pc += uint64(length)
	}
	return result
}

// isCallInsn reports whether disassembled text (riscv64asm.GoSyntax) is a
// call.  GoSyntax renders jal and jalr calls as CALL; the native mnemonics
// are accepted too.  The first token must match exactly: a prefix test on
// "bl" would catch branches on other architectures, and jalr as ret prints
// RET, which must not be stepped over.
func isCallInsn(text string) bool {
	m, _, _ := strings.Cut(text, " ")
	switch strings.ToLower(m) {
	case "call", "jal", "jalr":
		return true
	}
	return false
}