#include <ctype.h>

#include <kore/kore.h>
#include <kore/http.h>
#include <kore/pgsql.h>
#include <kore/seccomp.h>

#include "../lib/md4c/src/entity.h"
#include "../lib/md4c/src/entity.c"
#include "../lib/md4c/src/md4c.h"
#include "../lib/md4c/src/md4c.c"
#include "../lib/md4c/src/md4c-html.h"
#include "../lib/md4c/src/md4c-html.c"

#include "assets.h"
// FIXME: Why does compilation fail if this is a .c file?
#include "queries.h"

KORE_SECCOMP_FILTER("clog",
    KORE_SYSCALL_ALLOW(bind),
    KORE_SYSCALL_ALLOW(getdents64),
    KORE_SYSCALL_ALLOW(newfstatat),
    KORE_SYSCALL_ALLOW(sendmmsg),
    KORE_SYSCALL_ALLOW(uname)
)

enum request_type { JSON, HTML };

struct post_request {
	struct http_request *req;
	const char *resource;
	enum request_type type;

	int resp_status;
	struct kore_buf *resp_buf;
};

static const char *accept_json = "application/json";
static const char *database = "db";

static const char * const error_msg[] = {
	[HTTP_STATUS_NOT_FOUND] = "Resource not found.",
	[HTTP_STATUS_INTERNAL_ERROR] = "There was an error processing the request.",
};

void post_request_init(struct post_request *post_req);
void post_request_cleanup(struct post_request *post_req);

int validate_uuid(const char *input);

int redirect(struct http_request *req);

int post(struct http_request *req);
int posts(struct http_request *req);

int render_posts(struct http_request *req, const char *resource);
int render_posts_query(struct post_request *post_req);

int toy(struct http_request *req);

static void process_md_output(const MD_CHAR *, MD_SIZE size, void *);
static int render_md(const char *, struct kore_buf *);

void
post_request_init(struct post_request *post_req) {
	post_req->req = NULL;
	post_req->resource = NULL;
	post_req->type = JSON;

	post_req->resp_status = HTTP_STATUS_OK;
	post_req->resp_buf = kore_buf_alloc(0);
}

void
post_request_cleanup(struct post_request *post_req) {
	if (post_req->resp_buf != NULL)
		kore_buf_free(post_req->resp_buf);
	post_req->resp_buf = NULL;
}

int
validate_uuid(const char *input) {
	int i = 0;
	const char *p = NULL;

	if (strlen(input) != 36)
		return KORE_RESULT_ERROR;

	for (i = 0, p = input; i <= 36; i++) {
		if ((i == 8) || (i == 13) || (i == 18) || (i == 23)) {
			if (p[i] != '-')
				return KORE_RESULT_ERROR;
			continue;
		}
		if (i == 36) {
			if (p[i] != '\0')
				return KORE_RESULT_ERROR;
			continue;
		}
		if (!isxdigit(p[i]))
			return KORE_RESULT_ERROR;
	}

	return KORE_RESULT_OK;
}

int
redirect(struct http_request *req) {
	http_response_header(req, "Location", "/");
	http_response(req, HTTP_STATUS_MOVED_PERMANENTLY, NULL, 0);

	return KORE_RESULT_OK;
}

int
post(struct http_request *req) {
	const char *resource = NULL;

	resource = req->path + strlen("/posts/");
	kore_log(LOG_DEBUG, "Resource /posts/%s", resource);

	return render_posts(req, resource);
}

int
posts(struct http_request *req) {
	return render_posts(req, NULL);
}

int
render_posts(struct http_request *req, const char *resource) {
	int err = 0;

	const char *accept = NULL;

	struct post_request post_req;

	post_request_init(&post_req);

	post_req.req = req;
	post_req.resource = resource;

	err = http_request_header(req, "accept", &accept);
	if (err == KORE_RESULT_OK) {
		kore_log(LOG_DEBUG, "Accept: %s", accept);
		if (strncmp(accept, accept_json, sizeof(*accept_json)) == 0)
			post_req.type = JSON;
		else
			post_req.type = HTML;
	}

	if (post_req.type == JSON) {
		http_response_header(post_req.req, "content-type", "application/json; charset=utf-8");

		(void) render_posts_query(&post_req);
		if (post_req.resp_status != HTTP_STATUS_OK) {
			kore_buf_appendf(
				post_req.resp_buf,
				(const char *) asset_error_json,
				error_msg[post_req.resp_status]
			);
		}

	} else {
		http_response_header(post_req.req, "content-type", "text/html; charset=utf-8");

		kore_buf_append(post_req.resp_buf, asset_index_begin_html, asset_len_index_begin_html);

		(void) render_posts_query(&post_req);
		if (post_req.resp_status != HTTP_STATUS_OK) {
			kore_buf_appendf(
				post_req.resp_buf,
				(const char *) asset_error_html,
				error_msg[post_req.resp_status]
			);
		}

		kore_buf_append(post_req.resp_buf, asset_index_end_html, asset_len_index_end_html);
	}

	http_response(
		post_req.req,
		post_req.resp_status,
		post_req.resp_buf->data,
		post_req.resp_buf->offset
	);

	post_request_cleanup(&post_req);

	return KORE_RESULT_OK;
}


int
render_posts_query(struct post_request *post_req) {
	int err = 0;

	int row = 0, rows = 0;

	const char *id = NULL;
	const char *title = NULL;
	const char *created_at = NULL;
	const char *body = NULL;

	const char *json = NULL;

	struct kore_pgsql sql;

	kore_pgsql_init(&sql);

	// TODO use kore validation here.
	if (post_req->resource) {
		// Check for valid resource ID/UUID
		err = validate_uuid(post_req->resource);
		if (err == KORE_RESULT_ERROR) {
			post_req->resp_status = HTTP_STATUS_NOT_FOUND;
			kore_log(LOG_ERR, "Invalid post UUID %s.", post_req->resource);
			goto out;
		}
	}

	// Initialize our kore_pgsql data structure with the database name
	// we want to connect to (note that we registered this earlier with
	// kore_pgsql_register()). We also say we will perform a synchronous
	// query (KORE_PGSQL_SYNC).
	err = kore_pgsql_setup(&sql, database, KORE_PGSQL_SYNC);
	if (err == KORE_RESULT_ERROR) {
		post_req->resp_status = HTTP_STATUS_INTERNAL_ERROR;
		kore_pgsql_logerror(&sql);
		goto out;
	}

	// Query for posts, check for error.
	if (post_req->resource) {
		// Query a post.
		err = kore_pgsql_query_params(
			&sql,
			post_req->type == HTML ? query_html_post : query_json_post,
			0,  // return string data
			1,  // param count
			KORE_PGSQL_PARAM_TEXT(post_req->resource)
		);
	} else {
		// Query all posts.
		err = kore_pgsql_query(
			&sql,
			post_req->type == HTML ? query_html_posts : query_json_posts
		);
	}

	if (err == KORE_RESULT_ERROR) {
		post_req->resp_status = HTTP_STATUS_INTERNAL_ERROR;
		kore_pgsql_logerror(&sql);
		goto out;
	}

	if (post_req->type == JSON) {
		// XXX Always tuples from the above Postgres queries, need to check the length for results.
		if (kore_pgsql_getlength(&sql, 0, 0) == 0) {
			post_req->resp_status = HTTP_STATUS_NOT_FOUND;
			goto out;
		}

		json = kore_pgsql_getvalue(&sql, 0, 0);
		kore_buf_append(
			post_req->resp_buf,
			json,
			strlen(json)
		);
	} else { // post_req->type == HTML
		rows = kore_pgsql_ntuples(&sql);
		// FIXME: add test for this: 
		// if (post_req->resource && rows == 0) {
		if (rows == 0) {
			post_req->resp_status = HTTP_STATUS_NOT_FOUND;
			goto out;
		}

		// Iterate over posts and render them.
		for (row = 0; row < rows; row++) {
			id = kore_pgsql_getvalue(&sql, row, 0);
			title = kore_pgsql_getvalue(&sql, row, 1);
			created_at = kore_pgsql_getvalue(&sql, row, 2);
			body = kore_pgsql_getvalue(&sql, row, 3);
			kore_log(LOG_DEBUG, "id: '%s'; title '%s'", id, title);

			// Allocate a buffer to render the markdown as HTML into.
			struct kore_buf *html_buf = kore_buf_alloc(0);

			// Render MD.
			err = render_md(body, html_buf);
			if (err == KORE_RESULT_ERROR) {
				kore_log(LOG_ERR, "Error rendering markdown for entry %s.", id);
				kore_buf_free(html_buf);
				continue;
			}

			// Append rendered MD post.
			kore_buf_appendf(
				post_req->resp_buf,
				(const char *) asset_post_html,
				title,
				created_at,
				kore_buf_stringify(html_buf, NULL)
			);

			kore_buf_free(html_buf);
		}
	}

out: ;

	kore_pgsql_cleanup(&sql);

	return KORE_RESULT_OK;
}

int
toy(struct http_request *req) {
	int err = 0;

	int status = HTTP_STATUS_OK;

	struct kore_pgsql sql;

	kore_pgsql_init(&sql);

	err = kore_pgsql_setup(&sql, database, KORE_PGSQL_SYNC);
	if (err == KORE_RESULT_ERROR) {
		status = HTTP_STATUS_INTERNAL_ERROR;
		kore_pgsql_logerror(&sql);
		goto out;
	}

	// Query a post.
	err = kore_pgsql_query(
		&sql,
		"INSERT INTO posts (id, title, body) VALUES ('00000000-0000-0000-0000-000000000000', 'title', 'body');"
		                                          // 'af5bbaec-8d2b-11ed-9bf3-db5637a87ac5'
	);

	if (err == KORE_RESULT_ERROR) {
		status = HTTP_STATUS_INTERNAL_ERROR;
		kore_pgsql_logerror(&sql);
		goto out;
	}

out: ;

	kore_pgsql_cleanup(&sql);

	http_response(req, status, NULL, 0);

	return KORE_RESULT_OK;
}

static int
render_md(const char *in, struct kore_buf *out) {
	int err = 0;

	static unsigned parser_flags = 0;
	static unsigned renderer_flags = MD_HTML_FLAG_DEBUG;

	err = md_html(
		in,
		(MD_SIZE) strlen(in),
		process_md_output,
		(void*) out,
		parser_flags,
		renderer_flags
	);

	if(err != 0) {
		kore_log(LOG_ERR, "Parsing Markdown failed.");
		return KORE_RESULT_ERROR;
	}

	return KORE_RESULT_OK;
}

static void
process_md_output(const MD_CHAR *html, MD_SIZE size, void *buf) {
	kore_buf_append(
		(struct kore_buf *) buf,
		(const void *) html,
		(size_t) size
	);
}