package main

import (
	"fmt"
	"regexp"
	"strconv"
	"os"
)

var print = fmt.Println

func readfile(path string) []string {

	var raw []string;
	reg := regexp.MustCompile(`\s`)

	dat, err := os.ReadFile(path);
	if (err != nil) {
		panic("failed to read file");
	}

	tmp := reg.Split(string(dat), -1);
	/* TODO: add comments */

	for i := range tmp {
		if tmp[i] != "" {
			raw = append(raw, tmp[i]);
		}
	};

	return raw;
}

func parseString(raw[] string, i int) (str string, strLen int, endIndex int) {
	str = ""
	for ;; i++ {
		word := raw[i]
		strLen += len(word)
		str += word
		if word[len(word) - 1] == '"' {
			break;
		}
		str += " "
		strLen++
	}

	return  str, strLen, i
}

func compile(raw[]string) {
	var iflabels[] int
	var looplabels[] int
	var strings[][2] string

	print("section .text")
	print("global _start")
	print("_start:")

	for i := 0; i < len(raw); i++ {
		number, err := strconv.Atoi(raw[i]);
		if err == nil {
			print("		;; PUSHING TO STACK")
			print("		push", number)
			continue;
		}

		switch raw[i] {
		case "+":
			print("		;; PLUS")
			print("		pop rsi")
			print("		pop rax")
			print("		add rax, rsi")
			print("		push rax")

		case "-":
			print("		;; MINUS")
			print("		pop rsi")
			print("		pop rax")
			print("		sub rax, rsi")
			print("		push rax")

		case ">":
			print("		;; GREATER")
			print("		mov r10, 0")
			print("		mov r11, 1")
			print("		pop rsi")
			print("		pop rax")
			print("		cmp rax, rsi")
			print("		cmovg r10, r11")
			print("		push r10")

		case "<":
			print("		;; LESS")
			print("		mov r10, 0")
			print("		mov r11, 1")
			print("		pop rsi")
			print("		pop rax")
			print("		cmp rax, rsi")
			print("		cmovl r10, r11")
			print("		push r10")

		case "=":
			print("		;; EQUAL")
			print("		mov r10, 0")
			print("		mov r11,  1")
			print("		pop rsi")
			print("		pop rax")
			print("		cmp rax, rsi")
			print("		cmove r10, r11")
			print("		push r10")

		case ".":
			print("		;; DUMP")
			print("		pop rdi")
			print("		call .dump")

		case "dup":
			print("		;; DUPLICATE")
			print("		pop r10")
			print("		push r10")
			print("		push r10")

		case "if":
			print("		;; IF")
			print("		pop r10")
			print("		cmp r10, 0")
			fmt.Printf("		je .if%d\n", i)
			iflabels = append(iflabels, i)

		case "else":
			print("		;; ELSE")
			fmt.Printf("		jmp .if%d\n", i)
			fmt.Printf(".if%d:\n", iflabels[len(iflabels) - 1])
			iflabels = iflabels[:len(iflabels) - 1]
			iflabels = append(iflabels, i)

		case "endif":
			print("		;; ENDIF")
			fmt.Printf(".if%d:\n", iflabels[len(iflabels) - 1])
			iflabels = iflabels[:len(iflabels) - 1]

		case "while":
			print("		;; WHILE")
			fmt.Printf(".loop%d:\n", i);
			looplabels = append(looplabels, i)

		case "do":
			print("		;; DO")
			print("		pop r10")
			print("		cmp r10, 0")
			fmt.Printf("		je .endloop%d\n", looplabels[len(looplabels) - 1])

		case "endloop":
			print("		;; ENDLOOP")
			fmt.Printf("		jmp .loop%d\n", looplabels[len(looplabels) - 1])
			fmt.Printf(".endloop%d:\n", looplabels[len(looplabels) - 1])
			looplabels = looplabels[:len(looplabels) - 1]

		case "pushstr":
			str, strLen, lastIndex := parseString(raw, i + 1)

			print("		;; PUSHING STRING LENGTH")
			fmt.Printf("		push %d\n", strLen)
			print("		;; PUSHING STRING")
			fmt.Printf("		push string_%d\n", i);
			tmp := [2]string{str, fmt.Sprintf("string_%d", i)}
			strings = append(strings, tmp)
			i = lastIndex;
		/* Functions */
		case "exit":
			print("		;; EXIT")
			print("		pop rdi")
			print("		mov rax, 60")
			print("		syscall")

		case "println":
			print("		;; PRINTLN")
			print("		pop rsi")
			print("		pop rdx")
			print("		mov rdi, 1")
			print("		mov rax, 1")
			print("		syscall")
			print("		push rsi")
			print("		push rdx")

		default:
			panic("invalid word")
		}
	}

	print("		;; EXIT")
	print("		mov rdi, 0")
	print("		mov rax, 60")
	print("		syscall")


	print(".dump:");
	print("		push    rbp")
	print("		mov     rbp, rsp")
	print("		sub     rsp, 48")
	print("		mov     DWORD  [rbp-36], edi")
	print("		mov     QWORD  [rbp-32], 0")
	print("		mov     QWORD  [rbp-24], 0")
	print("		mov     DWORD  [rbp-16], 0")
	print("		mov     BYTE  [rbp-13], 10")
	print("		mov     DWORD  [rbp-4], 18")
	print("		mov     DWORD  [rbp-8], 0")
	print("		cmp     DWORD  [rbp-36], 0")
	print("		jns     .L3")
	print("		neg     DWORD  [rbp-36]")
	print("		mov     DWORD  [rbp-8], 1")
	print(".L3:")
	print("		mov     edx, DWORD  [rbp-36]")
	print("		movsx   rax, edx")
	print("		imul    rax, rax, 1717986919")
	print("		shr     rax, 32")
	print("		mov     ecx, eax")
	print("		sar     ecx, 2")
	print("		mov     eax, edx")
	print("		sar     eax, 31")
	print("		sub     ecx, eax")
	print("		mov     eax, ecx")
	print("		sal     eax, 2")
	print("		add     eax, ecx")
	print("		add     eax, eax")
	print("		sub     edx, eax")
	print("		mov     DWORD  [rbp-12], edx")
	print("		mov     eax, DWORD  [rbp-12]")
	print("		add     eax, 48")
	print("		mov     edx, eax")
	print("		mov     eax, DWORD  [rbp-4]")
	print("		cdqe")
	print("		mov     BYTE  [rbp-32+rax], dl")
	print("		mov     eax, DWORD  [rbp-12]")
	print("		sub     DWORD  [rbp-36], eax")
	print("		mov     eax, DWORD  [rbp-36]")
	print("		movsx   rdx, eax")
	print("		imul    rdx, rdx, 1717986919")
	print("		shr     rdx, 32")
	print("		mov     ecx, edx")
	print("		sar     ecx, 2")
	print("		cdq")
	print("		mov     eax, ecx")
	print("		sub     eax, edx")
	print("		mov     DWORD  [rbp-36], eax")
	print("		sub     DWORD  [rbp-4], 1")
	print("		cmp     DWORD  [rbp-36], 0")
	print("		jne     .L3")
	print("		cmp     DWORD  [rbp-8], 0")
	print("		je      .L4")
	print("		mov     eax, DWORD  [rbp-4]")
	print("		cdqe")
	print("		mov     BYTE  [rbp-32+rax], 45")
	print("		sub     DWORD  [rbp-4], 1")
	print(".L4:")
	print("		mov     eax, 20")
	print("		sub     eax, DWORD  [rbp-4]")
	print("		cdqe")
	print("		mov     edx, DWORD  [rbp-4]")
	print("		movsx   rdx, edx")
	print("		lea     rcx, [rbp-32]")
	print("		add     rcx, rdx")
	print("		mov     rdx, rax")
	print("		mov     rsi, rcx")
	print("		mov     edi, 1")
	print("		mov 	rax, 1")
	print("		syscall")
	print("		nop")
	print("		leave")
	print("		ret")

	print("section .data")
	for i := 0; i < len(strings); i++ {
		fmt.Printf("%s: db %s, 10\n", strings[i][1], strings[i][0])
	}
	print("")

}

func main() {
	argv := os.Args;
	argc := len(argv);

	if (argc != 2) {
		panic("Invaid usage");
	}

	raw := readfile(argv[argc - 1])
	compile(raw);
}