#define _POSIX_C_SOURCE 200809L
#include <unistd.h>
#include <spawn.h>
#include <sys/wait.h>

#include "codegen.h"
#include "cgC.h"
#include "messages.h"
#include "libs/stb_ds.h"

/* (Std)In --> process --> (Std)Out */
void
spawn_with_iofp(const char *path, char *const *argv,
					 pid_t *pid, FILE **in, FILE **out)
{
	int irp[2], asmp[2];
	posix_spawn_file_actions_t fileacts;
	posix_spawn_file_actions_init(&fileacts);

	if (in != nil) {
		/* the "in" pipe */
		if (pipe(irp) < 0)
			fatal(nil, nil, "could not open pipe");
		posix_spawn_file_actions_addclose(&fileacts, irp[1]);
		posix_spawn_file_actions_adddup2(&fileacts, irp[0], STDIN_FILENO);
	}
	if (out != nil) {
		/* the "out" pipe */
		if (pipe(asmp) < 0)
			fatal(nil, nil, "could not open pipe");
		posix_spawn_file_actions_addclose(&fileacts, asmp[0]);
		posix_spawn_file_actions_adddup2(&fileacts, asmp[1], STDOUT_FILENO);
	}

	if (posix_spawn(pid, path, &fileacts, nil, argv, nil) != 0)
		fatal(nil, nil, "posix_spawn failed");

	posix_spawn_file_actions_destroy(&fileacts);

	if (in != nil) {
		close(irp[0]);
		if ((*in = fdopen(irp[1], "wb")) == nil)
			fatal(nil, nil, "fdopen fail");
	}
	if (out != nil) {
		close(asmp[1]);
		if ((*out = fdopen(asmp[0], "rb")) == nil)
			fatal(nil, nil, "fdopen fail");
	}
}

void
process_wait(pid_t pid)
{
	int pstat;
	waitpid(pid, &pstat, 0);
	if (!WIFEXITED(pstat))
		fatal(nil, nil, "qbe crashed");
	/* did not crash, read return status */
	int exitc;
	if ((exitc = WEXITSTATUS(pstat)) != 0)
		fatal(nil, nil, "qbe exited with non-zero status %d", exitc);
}


CodegenCtx *
codegen_new(Compiler *cm, enum CodegenBackends backend)
{
	CodegenCtx *ctx = calloc(1, sizeof(*ctx));
	ctx->ext_pid = ctx->ld_pid = -1;
	ctx->backend = backend;
	ctx->cctx = cm;

	sh_new_arena(ctx->strings);
	shdefault(ctx->strings, -1);
	return ctx;
}

void
codegen_destroy(CodegenCtx *cgctx)
{
	if (cgctx->ext_pid != -1)
		process_wait(cgctx->ext_pid);
	if (cgctx->ld_pid != -1)
		process_wait(cgctx->ld_pid);
	shfree(cgctx->strings);	
	free(cgctx);
}

void
codegen(CodegenCtx *cgctx, Ast *program)
{
	switch (cgctx->backend) {
	case CgBackendC:
		cgC(&(CodegenC){.cgctx = cgctx, .indent = 2}, program);
		break;
	case CgBackendLibGccJit:
		fatal(nil, nil, "libgccjit backend not implemented yet");
		break;
	}
}