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

#include "assets.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"

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

int redirect(struct http_request *);

int post(struct http_request *);
int posts(struct http_request *);
int render_posts_html(struct http_request *, const char *);
int render_posts_json(struct http_request *, const char *);
static void process_md_output(const MD_CHAR *, MD_SIZE size, void *);
static int render_md(const char *, struct kore_buf *);

static const char *database = "db";

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

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)
{
	int err = 0;

	const char *accept = NULL;
	const char *resource = NULL;

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

	return render_posts_html(req, resource);
}

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

	const char *accept = NULL;

	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)
		{
			return render_posts_json(req, NULL);
		}
	}

	return render_posts_html(req, NULL);
}

int
render_posts_html(struct http_request *req, const char *resource)
{
	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;

	struct kore_buf *resp_buf = kore_buf_alloc(0);

	struct kore_pgsql sql;

	kore_pgsql_init(&sql);

	kore_buf_append(resp_buf, asset_index_begin_html, asset_len_index_begin_html);

	// 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)
	{
		kore_buf_appendf(
			resp_buf,
			(const char *) asset_error_html,
			"There was an error processing the request."
		);
		kore_pgsql_logerror(&sql);
		goto out;
	}

	// Query for posts, check for error.
	if (resource)
	{
		// Query a post.
		err = kore_pgsql_query_params(
			&sql,
			"SELECT id, title, created_at::DATE, body "
			"FROM posts "
			"WHERE id = $1;",
			0,  // return string data
			1,  // param count
			KORE_PGSQL_PARAM_TEXT(resource)
		);
	}
	else
	{
		// Query all posts.
		err = kore_pgsql_query(
			&sql,
			"SELECT id, title, created_at::DATE, body "
			"FROM posts "
			"ORDER BY updated_at DESC;"
		);
	}

	if (err == KORE_RESULT_ERROR)
	{
		kore_buf_appendf(
			resp_buf,
			(const char *) asset_error_html,
			"There was an error processing the request."
		);
		kore_pgsql_logerror(&sql);
		goto out;
	}

	// Iterate over posts and render them.
	rows = kore_pgsql_ntuples(&sql);
	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(
			resp_buf,
			(const char *) asset_post_html,
			title,
			created_at,
			kore_buf_stringify(html_buf, NULL)
		);

		kore_buf_free(html_buf);
	}

out: ;

	kore_buf_append(resp_buf, asset_index_end_html, asset_len_index_end_html);
	http_response_header(req, "content-type", "text/html; charset=utf-8");
	http_response(req, HTTP_STATUS_OK, resp_buf->data, resp_buf->offset);

	kore_pgsql_cleanup(&sql);
	kore_buf_free(resp_buf);

	return KORE_RESULT_OK;
}

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

	int rows = 0;

	const char *json = NULL;

	struct kore_buf *resp_buf = kore_buf_alloc(0);

	struct kore_pgsql sql;

	kore_pgsql_init(&sql);

	err = kore_pgsql_setup(&sql, database, KORE_PGSQL_SYNC);
	if (err == KORE_RESULT_ERROR)
	{
		kore_buf_appendf(
			resp_buf,
			(const char *) asset_error_html,
			"There was an error processing the request."
		);
		kore_pgsql_logerror(&sql);
		goto out;
	}

	if (resource)
	{
		err = kore_pgsql_query_params(
			&sql,
			"SELECT JSON_AGG(ROW_TO_JSON(row)) FROM ("
				"SELECT id, title, body, created_at, updated_at "
				"FROM posts "
				"WHERE id = $1"
			") row;",
			0,  // string data
			1,  // param count
			KORE_PGSQL_PARAM_TEXT(resource)
		);
	}
	else
	{
		err = kore_pgsql_query(
			&sql,
			"SELECT JSON_AGG(ROW_TO_JSON(row)) FROM ("
				"SELECT id, title, body, created_at, updated_at "
				"FROM posts "
				"ORDER BY updated_at DESC"
			") row;"
		);
	}
	if (err == KORE_RESULT_ERROR)
	{
		kore_buf_appendf(
			resp_buf,
			(const char *) asset_error_html,
			"There was an error processing the request."
		);
		kore_pgsql_logerror(&sql);
		goto out;
	}

	rows = kore_pgsql_ntuples(&sql);
	if (rows == 1) {
		json = kore_pgsql_getvalue(&sql, 0, 0);
		kore_buf_append(
			resp_buf,
			json,
			strlen(json)
		);
	} // else {

out: ;

	http_response_header(req, "content-type", "application/json; charset=utf-8");
	http_response(req, HTTP_STATUS_OK, resp_buf->data, resp_buf->offset);

	kore_pgsql_cleanup(&sql);
	kore_buf_free(resp_buf);

	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.\n");
		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);
}