#include "response.h"

#include <stdlib.h>
#include <string.h>
#include <stdio.h>

// Status text lookup
static const char* get_status_text(int code) {
	switch (code) {
		case 200: return "OK";
		case 201: return "Created";
		case 204: return "No Content";
		case 301: return "Moved Permanently";
		case 302: return "Found";
		case 304: return "Not Modified";
		case 400: return "Bad Request";
		case 401: return "Unauthorized";
		case 403: return "Forbidden";
		case 404: return "Not Found";
		case 405: return "Method Not Allowed";
		case 500: return "Internal Server Error";
		case 502: return "Bad Gateway";
		case 503: return "Service Unavailable";
		default: return "Unknown";
	}
}

// response_new creates a new response.
response_t* response_new(void) {
	response_t *res = calloc(1, sizeof(response_t));
	if (!res) return NULL;

	res->status_code = 200;
	res->body_cap = 8192;
	res->body = malloc(res->body_cap);

	return res;
}

// response_free destroys a response.
void response_free(response_t *res) {
	if (!res) return;

	response_header_t *h = res->headers;
	while (h) {
		response_header_t *next = h->next;
		free(h->name);
		free(h->value);
		free(h);
		h = next;
	}

	free(res->body);
	free(res);
}

// response_reset clears the response.
void response_reset(response_t *res) {
	res->status_code = 200;
	res->status_text = NULL;

	// Clear headers
	response_header_t *h = res->headers;
	while (h) {
		response_header_t *next = h->next;
		free(h->name);
		free(h->value);
		free(h);
		h = next;
	}
	res->headers = NULL;

	res->body_len = 0;
	res->headers_sent = 0;
}

// response_status sets the status code.
response_t* response_status(response_t *res, int code) {
	res->status_code = code;
	return res;
}

// response_header adds a header.
response_t* response_header(response_t *res, const char *name, const char *value) {
	response_header_t *h = malloc(sizeof(response_header_t));
	if (!h) return res;

	h->name = strdup(name);
	h->value = strdup(value);
	h->next = res->headers;
	res->headers = h;

	return res;
}

// response_content_type sets Content-Type header.
response_t* response_content_type(response_t *res, const char *type) {
	return response_header(res, "Content-Type", type);
}

// response_content_length sets Content-Length header.
response_t* response_content_length(response_t *res, size_t len) {
	char buf[32];
	snprintf(buf, sizeof(buf), "%zu", len);
	return response_header(res, "Content-Length", buf);
}

// ensure_capacity ensures body buffer has enough space.
static int ensure_capacity(response_t *res, size_t needed) {
	if (res->body_len + needed > res->body_cap) {
		size_t new_cap = res->body_cap * 2;
		while (new_cap < res->body_len + needed) new_cap *= 2;

		char *new_body = realloc(res->body, new_cap);
		if (!new_body) return -1;

		res->body = new_body;
		res->body_cap = new_cap;
	}
	return 0;
}

// response_body sets the body.
response_t* response_body(response_t *res, const char *data, size_t len) {
	if (ensure_capacity(res, len) < 0) return res;

	memcpy(res->body, data, len);
	res->body_len = len;

	return res;
}

// response_write appends to body.
response_t* response_write(response_t *res, const char *data, size_t len) {
	if (ensure_capacity(res, len) < 0) return res;

	memcpy(res->body + res->body_len, data, len);
	res->body_len += len;

	return res;
}

// response_text sends plain text.
response_t* response_text(response_t *res, int status, const char *text) {
	response_status(res, status);
	response_content_type(res, "text/plain");
	response_body(res, text, strlen(text));
	return res;
}

// response_html sends HTML.
response_t* response_html(response_t *res, int status, const char *html) {
	response_status(res, status);
	response_content_type(res, "text/html; charset=utf-8");
	response_body(res, html, strlen(html));
	return res;
}

// response_json sends JSON.
response_t* response_json(response_t *res, int status, const char *json) {
	response_status(res, status);
	response_content_type(res, "application/json");
	response_body(res, json, strlen(json));
	return res;
}

// response_redirect sends a redirect.
response_t* response_redirect(response_t *res, const char *url, int status) {
	if (status == 0) status = 302;
	response_status(res, status);
	response_header(res, "Location", url);
	return res;
}

// response_cookie sets a cookie.
response_t* response_cookie(response_t *res, const char *name, const char *value,
                           const char *path, int max_age, int http_only, int secure) {
	char cookie[1024];
	int len = snprintf(cookie, sizeof(cookie), "%s=%s", name, value);

	if (path) {
		len += snprintf(cookie + len, sizeof(cookie) - len, "; Path=%s", path);
	}

	if (max_age > 0) {
		len += snprintf(cookie + len, sizeof(cookie) - len, "; Max-Age=%d", max_age);
	}

	if (http_only) {
		len += snprintf(cookie + len, sizeof(cookie) - len, "; HttpOnly");
	}

	if (secure) {
		len += snprintf(cookie + len, sizeof(cookie) - len, "; Secure");
	}

	len += snprintf(cookie + len, sizeof(cookie) - len, "; SameSite=Lax");

	return response_header(res, "Set-Cookie", cookie);
}

// response_serialize writes response to buffer.
int response_serialize(response_t *res, char *buf, size_t size) {
	int len = 0;

	// Status line
	len = snprintf(buf, size, "HTTP/1.1 %d %s\r\n",
	              res->status_code, get_status_text(res->status_code));

	// Headers
	response_header_t *h = res->headers;
	while (h) {
		len += snprintf(buf + len, size - len, "%s: %s\r\n", h->name, h->value);
		h = h->next;
	}

	// Content-Length if body exists
	if (res->body_len > 0) {
		len += snprintf(buf + len, size - len, "Content-Length: %zu\r\n", res->body_len);
	}

	// End headers
	len += snprintf(buf + len, size - len, "\r\n");

	// Body
	if (res->body_len > 0 && len + res->body_len < size) {
		memcpy(buf + len, res->body, res->body_len);
		len += res->body_len;
	}

	return len;
}