package riscvemu

import (
	"bytes"
	"errors"
	"fmt"
	"os/exec"
	"strings"
	"testing"
)

// assemble_llvm assembles RISC-V source code with the installed system LLVM
// compiler and returns the raw bytes from the resulting .text section.
func assemble_llvm(source string) ([]byte, error) {
	// echo 'nop' | clang --target=riscv32 -march=rv32i -x assembler - -c -o - | llvm-objcopy - /dev/null --dump-section .text=/dev/stdout | xxd

	cmd := exec.Command(`/bin/bash`, `-c`, `/usr/bin/clang --target=riscv32 -march=rv32i -x assembler - -c -o - | /usr/bin/llvm-objcopy - /dev/null --dump-section .text=/dev/stdout`)
	cmd.Stdin = strings.NewReader(source)

	so_buff := bytes.Buffer{}
	cmd.Stdout = &so_buff

	err := cmd.Wait()
	if err != nil {
		return nil, err
	}

	return so_buff.Bytes(), nil
}

func runUntilEbreak(c *CPUState, expect_insns int) error {
	for i := 0; i < expect_insns-1; i++ {
		err := c.Step()
		if err != nil {
			return err
		}
	}

	err := c.Step()
	if err != nil {
		if eb := (ErrBreak{}); errors.As(err, &eb) {
			return nil // Successfully got EBREAK precisely when wanted
		}
		return err // Some other real error
	}

	return fmt.Errorf("Expected EBREAK at instruction count %d, but got %v", expect_insns, err)
}

func TestBreak(t *testing.T) {
	env := NewVirtualEEI()

	// ebreak
	_, err := env.WriteAt([]byte{0x73, 0x00, 0x10, 0x00}, 0)
	if err != nil {
		t.Fatal(err)
	}

	c := NewCPU(&env)

	err = c.Step()
	if err == nil {
		t.Fatal("expected ErrBreak, got <nil>")
	}
	if eb := (ErrBreak{}); !errors.As(err, &eb) {
		t.Fatalf("expected ErrBreak, got %#v", err)
	}
}

func TestAdd(t *testing.T) {
	env := NewVirtualEEI()

	// li a0, 0xffff
	// ebreak
	_, err := env.WriteAt([]byte{0x37, 0xc5, 0xad, 0xde, 0x13, 0x05, 0xf5, 0xee, 0x73, 0x00, 0x10, 0x00}, 0)
	if err != nil {
		t.Fatal(err)
	}

	c := NewCPU(&env)

	err = runUntilEbreak(&c, 3)
	if err != nil {
		t.Error(err)
	}

	// Check that we managed to load into the register
	if c.Registers[10] != 0xdeadbeef {
		t.Errorf("expected register a0 (x10) to contain 0xdeadbeef, got %#v", c.Registers[10])
	}
}