package compiler

import (
	"git.urbach.dev/cli/q/src/asm"
	"git.urbach.dev/cli/q/src/asmc"
	"git.urbach.dev/cli/q/src/config"
	"git.urbach.dev/cli/q/src/core"
	"git.urbach.dev/cli/q/src/x86"
)

// finalize generates the final machine code.
func (r *Result) finalize() {
	// This will be the entry point of the executable.
	// The only job of the entry function is to call `main` and exit cleanly.
	// The reason we call `main` instead of using `main` itself is to place
	// a return address on the stack, which allows return statements in `main`.
	final := asm.Assembler{
		Instructions: make([]asm.Instruction, 0, r.InstructionCount+8),
		Data:         make(map[string][]byte, r.DataCount),
	}

	r.Traversed = make(map[*core.Function]bool, len(r.Functions))

	// This will place the init function immediately after the entry point
	// and also add everything the init function calls recursively.
	r.eachFunction(r.Init, r.Traversed, func(f *core.Function) {
		final.Merge(f.Assembler)

		for _, library := range f.DLLs {
			for _, fn := range library.Functions {
				r.DLLs = r.DLLs.Append(library.Name, fn)
			}
		}
	})

	final.Label(asm.LABEL, "_crash")

	switch config.TargetOS {
	case config.Linux:
		final.RegisterNumber(asm.MOVE, x86.SyscallInputRegisters[0], LinuxExit)
		final.RegisterNumber(asm.MOVE, x86.SyscallInputRegisters[1], 1)
		final.Syscall()
	case config.Mac:
		final.RegisterNumber(asm.MOVE, x86.SyscallInputRegisters[0], MacExit)
		final.RegisterNumber(asm.MOVE, x86.SyscallInputRegisters[1], 1)
		final.Syscall()
	case config.Windows:
		final.RegisterNumber(asm.MOVE, x86.WindowsInputRegisters[0], 1)
		final.RegisterNumber(asm.AND, x86.RSP, -16)
		final.DLLCall("kernel32.ExitProcess")
	}

	r.Code, r.Data = asmc.Finalize(final, r.DLLs)
}