#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"
#include "queries.h"  // FIXME: Compilation fail if this is a .c file.

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 content_type { JSON, HTML };

enum query_status { QUERY_STATUS_OK, QUERY_STATUS_ERROR, QUERY_STATUS_NOT_FOUND };

struct post_query {
	char *id;
	enum content_type type;

	int status;
	struct kore_buf *result;
};

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

static const char * const error_msg[] = {
	[HTTP_STATUS_OK] = "OK",                                                        // 200
	[HTTP_STATUS_CREATED] = "Resource created successfully.",                       // 201
	[HTTP_STATUS_BAD_REQUEST] = "There was an error processing the request data.",  // 403?
	[HTTP_STATUS_NOT_FOUND] = "Resource not found.",                                // 404
	[HTTP_STATUS_INTERNAL_ERROR] = "There was an error processing the request.",    // 500
};

void post_query_init(struct post_query *pq, enum content_type type, const char *id);
void post_query_cleanup(struct post_query *pq);

int validate_uuid(const char *uuid);

enum content_type get_content_type(struct http_request *req);

int http_ok_resp(
	struct http_request *req,
	enum content_type type,
	enum http_status_code status,
	struct kore_buf *result
);

int http_err_resp(
	struct http_request *req,
	enum content_type type,
	enum http_status_code status
);

int redirect(struct http_request *req);

int get_posts(struct http_request *req);
int get_posts_resource(struct http_request *req);
int post_posts(struct http_request *req);
int delete_posts_resource(struct http_request *req);

int sql_select_posts(struct post_query *pq);
int sql_delete_posts(const char *id);
int sql_insert_posts(
	const char *id,
	const char *title,
	const char *body
);
int sql_render_posts(struct kore_pgsql *sql, struct post_query *pq);

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

void post_query_init(struct post_query *pq, enum content_type type, const char *id) {
	if (id != NULL)
		pq->id = kore_strdup(id);
	else
		pq->id = NULL;

	pq->type = type;

	pq->status = QUERY_STATUS_OK;
	pq->result = kore_buf_alloc(0);
}

void post_query_cleanup(struct post_query *pq) {
	if (pq->id != NULL)
		kore_free((void *) pq->id);
	pq->id = NULL;
	
	if (pq->result != NULL)
		kore_buf_free(pq->result);
	pq->result = NULL;
}

int validate_uuid(const char *uuid) {
	int i = 0;

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

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

	return KORE_RESULT_OK;
}

enum content_type get_content_type(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 JSON;
	}

	return HTML;
}

int http_ok_resp(
	struct http_request *req,
	enum content_type type,
	enum http_status_code status,
	struct kore_buf *result
) {
	struct kore_buf *resp_buf = kore_buf_alloc(0);
	const char *body = kore_buf_stringify(result, NULL);

	if (type == JSON) {
		http_response_header(req, "content-type", "application/json; charset=utf-8");
		kore_buf_append(
			resp_buf,
			body,
			strlen(body)
		);
	} else {
		http_response_header(req, "content-type", "text/html; charset=utf-8");
		kore_buf_append(resp_buf, asset_index_begin_html, asset_len_index_begin_html);
		kore_buf_append(
			resp_buf,
			body,
			strlen(body)
		);
		kore_buf_append(resp_buf, asset_index_end_html, asset_len_index_end_html);
	}

	http_response(
		req,
		status,
		resp_buf->data,
		resp_buf->offset
	);

	kore_buf_free(resp_buf);

	return KORE_RESULT_OK;
}

int http_err_resp(
	struct http_request *req,
	enum content_type type,
	enum http_status_code status
) {
	struct kore_buf *resp_buf = kore_buf_alloc(0);

	if (type == JSON) {
		http_response_header(req, "content-type", "application/json; charset=utf-8");
		kore_buf_appendf(
			resp_buf,
			(const char *) asset_error_json,
			error_msg[status]
		);
	} else {
		http_response_header(req, "content-type", "text/html; charset=utf-8");
		kore_buf_append(resp_buf, asset_index_begin_html, asset_len_index_begin_html);
		kore_buf_appendf(
			resp_buf,
			(const char *) asset_error_html,
			error_msg[status]
		);
		kore_buf_append(resp_buf, asset_index_end_html, asset_len_index_end_html);
	}

	http_response(
		req,
		status,
		resp_buf->data,
		resp_buf->offset
	);

	kore_buf_free(resp_buf);

	return KORE_RESULT_OK;
}

int redirect(struct http_request *req) {
	http_response_header(req, "Location", "/");
	http_response(req, HTTP_STATUS_TEMPORARY_REDIRECT, NULL, 0);
	return KORE_RESULT_OK;
}

int get_posts(struct http_request *req) {
	struct post_query pq;

	post_query_init(&pq, get_content_type(req), NULL);

	(void) sql_select_posts(&pq);
	if (pq.status != QUERY_STATUS_OK)
		http_err_resp(req, pq.type, HTTP_STATUS_INTERNAL_ERROR);
	else
		http_ok_resp(req, pq.type, HTTP_STATUS_OK, pq.result);

	post_query_cleanup(&pq);

	return KORE_RESULT_OK;
}

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

	struct post_query pq;

	post_query_init(&pq, get_content_type(req), req->path + strlen("/posts/"));

	// Check for valid resource UUID
	kore_log(LOG_DEBUG, "Resource id /posts/%s.", pq.id);
	err = validate_uuid(pq.id);
	if (err == KORE_RESULT_ERROR) {
		kore_log(LOG_ERR, "Invalid post id %s.", pq.id);
		http_err_resp(req, pq.type, HTTP_STATUS_NOT_FOUND);
		goto out;
	}

	(void) sql_select_posts(&pq);
	if (pq.status == QUERY_STATUS_NOT_FOUND)
		http_err_resp(req, pq.type, HTTP_STATUS_NOT_FOUND);
	else if (pq.status == QUERY_STATUS_ERROR)
		http_err_resp(req, pq.type, HTTP_STATUS_INTERNAL_ERROR);
	else
		http_ok_resp(req, pq.type, HTTP_STATUS_OK, pq.result);

out: ;

	post_query_cleanup(&pq);

	return KORE_RESULT_OK;
}

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

	int status = HTTP_STATUS_CREATED;

	enum content_type type = get_content_type(req);

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

	struct kore_json_item *item = NULL;
	struct kore_json json;

	kore_json_init(&json, req->http_body->data, req->http_body->length);

	if (!kore_json_parse(&json)) {
		status = HTTP_STATUS_BAD_REQUEST;
		kore_log(LOG_ERR, "error parsing json: %s\n", kore_json_strerror());
		goto out;
	}

	item = kore_json_find_string(json.root, "id");
	if (item != NULL) {
		id = item->data.string;
		kore_log(LOG_INFO, "id = '%s'\n", id);
		// Check for valid resource ID/UUID
		err = validate_uuid(id);
		if (err == KORE_RESULT_ERROR) {
			status = HTTP_STATUS_BAD_REQUEST;
			kore_log(LOG_ERR, "Invalid post UUID %s.", id);
			goto out;
		}
	}

	item = kore_json_find_string(json.root, "title");
	if (item != NULL) {
		title = item->data.string;
		kore_log(LOG_INFO, "title = '%s'\n", title);
	} else {
		status = HTTP_STATUS_BAD_REQUEST;
		kore_log(LOG_ERR, "error parsing title: %s\n", kore_json_strerror());
		goto out;
	}

	item = kore_json_find_string(json.root, "body");
	if (item != NULL) {
		body = item->data.string;
		kore_log(LOG_INFO, "body = '%s'\n", body);
	} else {
		status = HTTP_STATUS_BAD_REQUEST;
		kore_log(LOG_ERR, "error parsing body: %s\n", kore_json_strerror());
		goto out;
	}

	err = sql_insert_posts(id, title, body);

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

out: ;

	http_err_resp(req, type, status);

	kore_json_cleanup(&json);

	return KORE_RESULT_OK;
}

int sql_select_posts(struct post_query *pq) {
	int err = KORE_RESULT_OK;

	struct kore_pgsql sql;

	kore_pgsql_init(&sql);

	pq->status = QUERY_STATUS_OK;

	// Set up synchronous database handle.
	err = kore_pgsql_setup(&sql, database, KORE_PGSQL_SYNC);
	if (err == KORE_RESULT_ERROR) {
		pq->status = QUERY_STATUS_ERROR;
		kore_pgsql_logerror(&sql);
		goto out;
	}

	// Query for posts, check for error.
	if (pq->id != NULL) {
		// Query a post.
		err = kore_pgsql_query_params(
			&sql,
			pq->type == HTML ? q_select_html_post : q_select_json_post,
			0,  // return string data
			1,  // param count
			KORE_PGSQL_PARAM_TEXT(pq->id)
		);
	} else {
		// Query all posts.
		err = kore_pgsql_query(
		&sql,
			pq->type == HTML ? q_select_html_posts : q_select_json_posts
		);
	}

	if (err == KORE_RESULT_ERROR) {
		pq->status = QUERY_STATUS_ERROR;
		kore_pgsql_logerror(&sql);
		goto out;
	}

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

	// TODO: Add test for this; When database is empty, don't return 404 for base request.
	if (pq->id != NULL && kore_pgsql_ntuples(&sql) == 0) {
		pq->status = QUERY_STATUS_NOT_FOUND;
		goto out;
	}

	(void) sql_render_posts(&sql, pq);

out: ;

	kore_pgsql_cleanup(&sql);

	return err;
}

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

	enum content_type type = get_content_type(req);
	const char *id = req->path + strlen("/posts/");

	// Check for valid resource UUID
	kore_log(LOG_DEBUG, "Resource id /posts/%s.", id);
	err = validate_uuid(id);
	if (err == KORE_RESULT_ERROR) {
		kore_log(LOG_ERR, "Invalid post id %s.", id);
		http_err_resp(req, type, HTTP_STATUS_NOT_FOUND);
		goto out;
	}

	err = sql_delete_posts(id);
	// FIXME: should 404 if id doesn't exist.
	// if (pq.status == QUERY_STATUS_NOT_FOUND)
	// 	http_err_resp(req, pq.type, HTTP_STATUS_NOT_FOUND);
	if (err == KORE_RESULT_ERROR)
		http_err_resp(req, type, HTTP_STATUS_INTERNAL_ERROR);
	else
		// TODO: test this, it should explode.
		http_err_resp(req, type, HTTP_STATUS_OK);

out: ;

	return KORE_RESULT_OK;
}

int sql_render_posts(struct kore_pgsql *sql, struct post_query *pq) {
	int err = KORE_RESULT_OK;

	int row = 0, rows = 0;

	struct kore_buf *html_buf = NULL;

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

	if (pq->type == JSON) {
		kore_buf_append(
			pq->result,
			kore_pgsql_getvalue(sql, 0, 0),
			kore_pgsql_getlength(sql, 0, 0)
		);
		return KORE_RESULT_OK;
	}

	// pg->type == HTML

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

	// Iterate over posts and render them.
	rows = kore_pgsql_ntuples(sql);
	for (row = 0; row < rows; row++) {
		// Reset buffer.
		kore_buf_cleanup(html_buf);

		// Fetch data.
		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);

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

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

	}

	kore_buf_free(html_buf);

	return KORE_RESULT_OK;
}

int sql_insert_posts(const char *id, const char *title, const char *body) {
	int err = KORE_RESULT_OK;

	struct kore_pgsql sql;
	kore_pgsql_init(&sql);

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

	if (id == NULL) {
		err = kore_pgsql_query_params(
			&sql,
			q_insert_posts,
			0,
			2,
			KORE_PGSQL_PARAM_TEXT(title),
			KORE_PGSQL_PARAM_TEXT(body)
		);
	} else {
		err = kore_pgsql_query_params(
			&sql,
			q_insert_posts_with_id,
			0,
			3,
			KORE_PGSQL_PARAM_TEXT(id),
			KORE_PGSQL_PARAM_TEXT(title),
			KORE_PGSQL_PARAM_TEXT(body)
		);
	}
	if (err == KORE_RESULT_ERROR) {
		kore_pgsql_logerror(&sql);
		goto out;
	}

out: ;

	kore_pgsql_cleanup(&sql);

	return err;
}

int sql_delete_posts(const char *id) {
	int err = KORE_RESULT_OK;

	struct kore_pgsql sql;
	kore_pgsql_init(&sql);

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

	err = kore_pgsql_query_params(
		&sql,
		q_delete_posts,
		0,
		1,
		KORE_PGSQL_PARAM_TEXT(id)
	);
	if (err == KORE_RESULT_ERROR) {
		kore_pgsql_logerror(&sql);
		goto out;
	}

out: ;

	kore_pgsql_cleanup(&sql);

	return err;
}

static int render_md(const char *in, struct kore_buf *out) {
	// Not a kore err.
	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
	);
}