#include "request.h"

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

// request_new creates a new request.
request_t* request_new(arena_t *arena) {
	request_t *req = arena_alloc(arena, sizeof(request_t));
	if (!req) return NULL;

	memset(req, 0, sizeof(request_t));
	req->arena = arena;
	return req;
}

// parse_request_line parses the first line of HTTP request.
static int parse_request_line(request_t *req, const char *line, size_t len) {
	const char *p = line;
	const char *end = line + len;

	// Find method
	const char *method_end = memchr(p, ' ', end - p);
	if (!method_end) return -1;

	req->method = arena_strdup(req->arena, p, method_end - p);
	p = method_end + 1;

	// Find path (may include query string)
	const char *path_end = memchr(p, ' ', end - p);
	if (!path_end) return -1;

	// Check for query string
	const char *query = memchr(p, '?', path_end - p);
	if (query) {
		req->path = arena_strdup(req->arena, p, query - p);
		req->query_string = arena_strdup(req->arena, query + 1, path_end - query - 1);
	} else {
		req->path = arena_strdup(req->arena, p, path_end - p);
	}

	p = path_end + 1;

	// Find version
	const char *version_end = end;
	if (version_end > p && *(version_end - 1) == '\r') version_end--;

	req->version = arena_strdup(req->arena, p, version_end - p);

	return 0;
}

// add_header adds a header to the request.
static void add_header(request_t *req, const char *name, size_t name_len,
                       const char *value, size_t value_len) {
	header_t *h = arena_alloc(req->arena, sizeof(header_t));
	if (!h) return;

	h->name = arena_strdup(req->arena, name, name_len);
	h->value = arena_strdup(req->arena, value, value_len);
	h->next = req->headers;
	req->headers = h;
	req->header_count++;
}

// request_parse parses an HTTP request.
int request_parse(request_t *req, const char *buf, size_t len) {
	const char *p = buf;
	const char *end = buf + len;

	// Find end of request line
	const char *line_end = memchr(p, '\n', end - p);
	if (!line_end) return -1;

	// Parse request line
	if (parse_request_line(req, p, line_end - p) < 0) return -1;

	p = line_end + 1;

	// Parse headers
	while (p < end) {
		// Check for end of headers
		if (*p == '\r' && p + 1 < end && *(p + 1) == '\n') {
			p += 2;
			break;
		} else if (*p == '\n') {
			p++;
			break;
		}

		// Find header name
		const char *colon = memchr(p, ':', end - p);
		if (!colon) break;

		const char *name_end = colon;
		while (name_end > p && isspace(*(name_end - 1))) name_end--;

		// Find header value
		const char *value_start = colon + 1;
		while (value_start < end && isspace(*value_start)) value_start++;

		const char *value_end = memchr(value_start, '\n', end - value_start);
		if (!value_end) value_end = end;

		if (value_end > value_start && *(value_end - 1) == '\r') value_end--;

		// Add header
		add_header(req, p, name_end - p, value_start, value_end - value_start);

		p = value_end;
		if (p < end && *p == '\r') p++;
		if (p < end && *p == '\n') p++;
	}

	// Store body
	if (p < end) {
		req->body_len = end - p;
		req->body = arena_strdup(req->arena, p, req->body_len);
	}

	return 0;
}

// request_header returns a header value.
const char* request_header(request_t *req, const char *name) {
	header_t *h = req->headers;
	while (h) {
		if (strcasecmp(h->name, name) == 0) {
			return h->value;
		}
		h = h->next;
	}
	return NULL;
}

// request_has_header checks if header exists.
int request_has_header(request_t *req, const char *name) {
	return request_header(req, name) != NULL;
}

// request_set_params sets route parameters.
void request_set_params(request_t *req, char **names, char **values, int count) {
	req->param_names = names;
	req->param_values = values;
	req->param_count = count;
}

// request_param returns a route parameter.
const char* request_param(request_t *req, const char *name) {
	for (int i = 0; i < req->param_count; i++) {
		if (req->param_names[i] && strcmp(req->param_names[i], name) == 0) {
			return req->param_values[i];
		}
	}
	return NULL;
}

// parse_url_encoded parses application/x-www-form-urlencoded data.
static void parse_url_encoded(request_t *req, const char *data, size_t len,
                              char ***keys, char ***values, int *count) {
	if (!data || len == 0) return;

	// Count parameters
	int n = 1;
	for (size_t i = 0; i < len; i++) {
		if (data[i] == '&') n++;
	}

	*keys = arena_alloc(req->arena, n * sizeof(char*));
	*values = arena_alloc(req->arena, n * sizeof(char*));
	*count = 0;

	const char *p = data;
	const char *end = data + len;

	while (p < end) {
		// Find key
		const char *eq = memchr(p, '=', end - p);
		const char *amp = memchr(p, '&', end - p);

		if (!amp) amp = end;

		if (eq && eq < amp) {
			// Key=value pair
			(*keys)[*count] = arena_strdup(req->arena, p, eq - p);
			(*values)[*count] = arena_strdup(req->arena, eq + 1, amp - eq - 1);
			(*count)++;
		} else {
			// Key only
			(*keys)[*count] = arena_strdup(req->arena, p, amp - p);
			(*values)[*count] = "";
			(*count)++;
		}

		p = amp + 1;
	}
}

// request_parse_query parses query parameters.
int request_parse_query(request_t *req) {
	if (req->query_count > 0) return 0; // already parsed

	parse_url_encoded(req, req->query_string,
	                 req->query_string ? strlen(req->query_string) : 0,
	                 &req->query_keys, &req->query_values, &req->query_count);
	return 0;
}

// request_query returns a query parameter.
const char* request_query(request_t *req, const char *name) {
	request_parse_query(req);

	for (int i = 0; i < req->query_count; i++) {
		if (strcmp(req->query_keys[i], name) == 0) {
			return req->query_values[i];
		}
	}
	return NULL;
}

// request_parse_cookies parses cookies from Cookie header.
int request_parse_cookies(request_t *req) {
	if (req->cookie_count > 0) return 0; // already parsed

	const char *cookies = request_header(req, "Cookie");
	if (!cookies) return 0;

	// Count cookies
	int n = 1;
	for (const char *p = cookies; *p; p++) {
		if (*p == ';') n++;
	}

	req->cookie_names = arena_alloc(req->arena, n * sizeof(char*));
	req->cookie_values = arena_alloc(req->arena, n * sizeof(char*));
	req->cookie_count = 0;

	const char *p = cookies;
	while (*p) {
		// Skip whitespace
		while (*p && isspace(*p)) p++;
		if (!*p) break;

		// Find name
		const char *eq = strchr(p, '=');
		const char *semi = strchr(p, ';');

		if (!semi) semi = p + strlen(p);

		if (eq && eq < semi) {
			req->cookie_names[req->cookie_count] = arena_strdup(req->arena, p, eq - p);
			req->cookie_values[req->cookie_count] = arena_strdup(req->arena, eq + 1, semi - eq - 1);
			req->cookie_count++;
		}

		p = semi;
		if (*p == ';') p++;
	}

	return 0;
}

// request_cookie returns a cookie value.
const char* request_cookie(request_t *req, const char *name) {
	request_parse_cookies(req);

	for (int i = 0; i < req->cookie_count; i++) {
		if (strcmp(req->cookie_names[i], name) == 0) {
			return req->cookie_values[i];
		}
	}
	return NULL;
}

// request_body returns the request body.
const char* request_body(request_t *req) {
	return req->body;
}

// request_body_len returns the body length.
size_t request_body_len(request_t *req) {
	return req->body_len;
}

// request_content_type returns the content type.
const char* request_content_type(request_t *req) {
	const char *ct = request_header(req, "Content-Type");
	if (!ct) return NULL;

	// Return content type without charset
	static char type[128];
	const char *semi = strchr(ct, ';');
	if (semi) {
		size_t len = semi - ct;
		if (len >= sizeof(type)) len = sizeof(type) - 1;
		memcpy(type, ct, len);
		type[len] = '\0';
		return type;
	}

	return ct;
}

// request_is_json checks if request has JSON content.
int request_is_json(request_t *req) {
	const char *ct = request_content_type(req);
	return ct && strcmp(ct, "application/json") == 0;
}

// request_is_form checks if request has form data.
int request_is_form(request_t *req) {
	const char *ct = request_content_type(req);
	return ct && strcmp(ct, "application/x-www-form-urlencoded") == 0;
}

// request_expects_json checks if client expects JSON response.
int request_expects_json(request_t *req) {
	const char *accept = request_header(req, "Accept");
	if (accept && strstr(accept, "application/json")) return 1;

	const char *xhr = request_header(req, "X-Requested-With");
	if (xhr && strcmp(xhr, "XMLHttpRequest") == 0) return 1;

	return 0;
}