#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
#include <curl/curl.h>
#include <stdlib.h>
#include <string.h>

#include "lib.h"

typedef struct {
	char **segments;
	size_t *sizes;
	size_t n, cap;
} http_body_buff_t;

static size_t body_writer(char *ptr, size_t _, size_t size, void *pbuff) {
	http_body_buff_t *buff = pbuff;

	size_t new_cap = buff->cap;
	while (buff->n >= new_cap) {
		new_cap *= 2;
	}

	if (new_cap > buff->cap) {
		buff->segments = realloc(buff->segments, sizeof(*buff->segments) * new_cap);
		buff->sizes = realloc(buff->sizes, sizeof(*buff->sizes) * new_cap);
		buff->cap = new_cap;
	}

	buff->segments[buff->n] = malloc(size);
	memcpy(buff->segments[buff->n], ptr, size);
	buff->sizes[buff->n] = size;
	buff->n++;


	return size;
}

static char *body_compress(http_body_buff_t buff, size_t *psize) {
	size_t size = 0;

	for (size_t i = 0; i < buff.n; i++) {
		size += buff.sizes[i];
	}

	char *res = malloc(size + 1);
	res[size] = 0;

	size_t offset = 0;

	for (size_t i = 0; i < buff.n; i++) {
		memcpy(res + offset, buff.segments[i], buff.sizes[i]);
		offset += buff.sizes[i];
		free(buff.segments[i]);
	}

	free(buff.segments);
	free(buff.sizes);

	*psize = size;
	return res;
}

static int lib_http_get(lua_State *ctx) {
	const char *url = luaL_checkstring(ctx, 1);

	http_body_buff_t buff = {
		.segments = malloc(sizeof *buff.segments * 16),
		.sizes = malloc(sizeof *buff.sizes * 16),
		.n = 0,
		.cap = 16,
	};

	CURL *curl = curl_easy_init();
	curl_easy_setopt(curl, CURLOPT_URL, url);
	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, body_writer);
	curl_easy_setopt(curl, CURLOPT_WRITEDATA, &buff);

	CURLcode code = curl_easy_perform(curl);
	curl_easy_cleanup(curl);

	if (code != CURLE_OK) {
		return luaL_error(ctx, "HTTP GET failed: %s", curl_easy_strerror(code));
	}

	size_t size;
	char *body = body_compress(buff, &size);
	lua_pushlstring(ctx, body, size);
	free(body);

	return 1;
}

int http_open_lib(lua_State *ctx) {
	luaL_newlib(ctx, ((luaL_Reg[]) {
		{ "get", lib_http_get },
		{ NULL, NULL },
	}));

	return 1;
}