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mod.ts
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import { calculate, extract, log, parse, render, test } from "./deps.ts";
type DocMeta = {
etag: string;
timestamp: number;
body: string;
};
export type SnippetType = {
mdName?: string;
title?: string;
date?: Date;
dateStamp?: string;
teaser?: string;
};
type GenericSnippetFunc = <T extends SnippetType>(args: T) => string;
type Markdown = {
mdName: string;
mdContent: string;
};
type Frontmatter = {
mdName: string;
frontmatter: Record<string, unknown>;
};
export type ExternalLinksType = string[];
type TemplateType = (
html: string,
stylesheetlinks?: ExternalLinksType,
css?: string,
scripttaglinkslinks?: ExternalLinksType,
) => string;
type ServeZettelkastenType = {
conn: Deno.Conn;
template?: TemplateType;
snippet?: GenericSnippetFunc;
stylesheetlinks?: ExternalLinksType;
css?: string;
zettelResource: string;
keyValueStore: string;
ttl: number;
scripttaglinks?: ExternalLinksType;
};
type HomeHandlerType = {
template: TemplateType;
snippet: GenericSnippetFunc;
stylesheetlinks: ExternalLinksType;
css: string;
resource: string;
scripttaglinks?: ExternalLinksType;
};
type PathHandlerType = HomeHandlerType & {
pathname: string;
};
export const simpleTemplate = <TemplateType>(
body = "",
stylesheetlinks: ExternalLinksType = [],
css = "",
scripttaglinks: ExternalLinksType = [],
) => {
const stylesheets = stylesheetlinks.length > 0
? stylesheetlinks.map(
(styl) => `<link rel="stylesheet" href="${styl}" />`,
)
: "";
const scripttags = scripttaglinks.length > 0
? scripttaglinks.map(
(script) => `<script type="module" src="${script}"></script>`,
)
: "";
return `<!doctype html>
<html lang=en>
<head>
<meta charset=utf-8>
<title>Zettelkasten</title>
${stylesheets}
<style>
main {
max-width: 800px;
margin: 0 auto;
}
${css}
</style>
${scripttags}
</head>
<body>
<main data-color-mode="light" data-light-theme="light" data-dark-theme="dark" class="markdown-body">
${body}
</main>
</body>
</html>
`;
};
export const simpleSnippet = ({
mdName = "missing name",
title = "missing title",
date = new Date(),
dateStamp = "",
teaser = "missing teaser",
}: SnippetType) =>
`<section>
<h2><a href="/${mdName}">${title}</a></h2>
<time datetime="${date.toUTCString()}">${dateStamp}</time>
<span>${teaser}</span>
<span> - </span><time datetime="${date.toUTCString()}">${date.getFullYear()}/${date.getMonth()}/${date.getDay()}</time>
</section>`;
export async function validateDocs(
documentResponses: Response[],
documentList: string[],
) {
const validDocs = [];
for (const [i, doc] of documentResponses.entries()) {
const fileName = documentList[i];
try {
checkStatusCode(doc?.status, fileName);
} catch (_err) {
log.error(`HTTP status code ${doc?.status} for file ${fileName}`);
// Error with document, skip to next in loop
continue;
}
// Shave of ".md" file ending from file name
const mdName = fileName.split(".").slice(0, -1).join(".");
validDocs.push({ mdName, mdContent: await doc.text() });
}
return validDocs;
}
export function teaserifyDocs(documents: Markdown[]) {
const teasers: Frontmatter[] = [];
for (const doc of documents) {
if (!(typeof doc?.mdContent === "string")) continue;
if (!test(doc?.mdContent)) continue;
let teaser;
try {
teaser = generateDocument(doc);
} catch (err) {
log.error(`${err.message} while generating article.`);
continue;
}
teasers.push(teaser);
}
return teasers;
}
const checkResponse = (response: Response, resource: string) => {
// check if status code is 200
if (!response) {
throw new Error(`${resource} response is undefined`);
}
if (response.status === 502) {
throw new Error("Status code 502, Bad Gateway", {
cause: `${response.url} does not exist`,
});
}
if (response.status === 404) {
throw new Error(`Status code 404 for ${resource}`, {
cause: `${response.url} does not exist`,
});
}
if (response.status !== 200) {
throw new Error("Status code NOT 200 OK", {
cause: `${response.url} does not exist`,
});
}
};
const checkStatusCode = (statusCode: number | undefined, resource: string) => {
// check if status code is 200
if (statusCode !== 200) {
throw new Error(
`${resource} HTTP status code '${statusCode}' does not equal '200'`,
);
}
};
const checkContentType = (
contentType: string | null | undefined,
resource: string,
) => {
// check if content-type is not 'text/html', because we expect yaml or markdown
if (contentType === "text/html") {
throw new Error(
`${resource} HTTP content-type '${contentType}' is invalid`,
);
}
};
const handleNetworkError = () => {
return new Response("Bad Gateway: Network error while fetching...", {
status: 502,
});
};
const fetchArticles = async (fileName: string, resource: string) =>
await fetch(`${resource}${fileName}`).catch(handleNetworkError);
export const generateDocument = ({ mdName, mdContent }: Markdown) => {
const { attrs: frontmatter, body: markdown } = extract(mdContent);
if (!frontmatter) {
log.error("document doesn't contain front matter");
}
return {
mdName,
frontmatter,
markdown,
};
};
export function markupify(
{ mdName, frontmatter }: Frontmatter,
snippet: GenericSnippetFunc,
) {
const { title, date, teaser } = frontmatter as SnippetType;
const dateObj = date as Date;
const dateStamp = dateObj.toLocaleString("de-de").split(",")[0];
return snippet({
title,
date,
teaser,
mdName,
dateStamp,
});
}
async function homeHandler({
template,
snippet,
stylesheetlinks,
css,
resource,
scripttaglinks,
}: HomeHandlerType) {
const sitemapResource = "sitemap.yaml";
const sitemapResponse = await fetch(`${resource}${sitemapResource}`).catch(
handleNetworkError,
);
checkResponse(sitemapResponse, sitemapResource);
checkStatusCode(sitemapResponse?.status, sitemapResource);
checkContentType(
sitemapResponse?.headers?.get("Content-Type"),
sitemapResource,
);
const sitemapbody = await sitemapResponse?.text();
const parsedYamlDocList = parse(sitemapbody) as string[];
const docs = await Promise.all(
parsedYamlDocList.map((docname) => fetchArticles(docname, resource)),
);
const validDocs = await validateDocs(docs, parsedYamlDocList);
const teasers = await teaserifyDocs(validDocs);
const allSnippets = teasers.map((teaser) => markupify(teaser, snippet));
const body = template(
allSnippets?.join(""),
stylesheetlinks,
css,
scripttaglinks,
);
// back to the client.
const headers = new Headers({
"content-type": "text/html",
});
return { body, headers, status: 200 };
}
export async function pathHandler({
pathname,
template,
snippet,
stylesheetlinks,
css,
resource,
scripttaglinks,
}: PathHandlerType) {
log.info(`PATHNAME: ${pathname}`);
const mdName = pathname.substring(1);
const markdownDocResponse = await fetch(`${resource}${mdName}.md`).catch(
handleNetworkError,
);
checkStatusCode(markdownDocResponse?.status, mdName);
const mdContent = await markdownDocResponse.text();
test(mdContent);
const mdDoc = {
mdName,
mdContent,
};
const document = generateDocument(mdDoc);
const markup = markupify(document, snippet) +
render(document.markdown, {
mediaBaseUrl: resource,
});
const body = template(
markup?.toString(),
stylesheetlinks,
css,
scripttaglinks,
);
const headers = new Headers({
"content-type": "text/html",
});
return { body, headers, status: 200 };
}
async function reply(
ifNoneMatch: string | null,
pathname: string,
kv: Deno.Kv | undefined,
{
body,
headers,
status,
}: {
body: string;
headers: Headers;
status: number;
},
) {
const bodyEtag = await calculate(body);
if (kv) {
log.info("Will cache in KV");
kv.set([pathname], {
etag: `W/${bodyEtag}`,
timestamp: Number(new Date().getTime()),
body,
});
}
if (`W/${bodyEtag}` === ifNoneMatch) {
return new Response(null, {
headers: headers,
status: 304,
});
}
bodyEtag && headers.append("etag", bodyEtag);
return new Response(body, {
headers: headers,
status,
});
}
const smash = {
badImplementation(err: Error) {
log.error(`SMASH("Bad Implementation"): ${err}`);
return {
body: "HIDE ME: Bad Implementation",
headers: new Headers({
"content-type": "text/html",
}),
status: 500,
};
},
notImplemented(err: Error) {
log.error(`SMASH("Not Implemented"): ${err}`);
return {
body: "HIDE ME: Not Implemented",
headers: new Headers({
"content-type": "text/html",
}),
status: 501,
};
},
badGateway(err: Error) {
log.error(`SMASH("Bad Gateway"): ${err}`);
return {
body: "Bad Gateway",
headers: new Headers({
"content-type": "text/html",
}),
status: 502,
};
},
serverUnavailable(err: Error) {
log.error(`SMASH("Server Unavailable"): ${err}`);
return {
body: "Server Unavailable",
headers: new Headers({
"content-type": "text/html",
}),
status: 503,
};
},
gatewayTimeout(err: Error) {
log.error(`SMASH("Gateway Timeout"): ${err}`);
return {
body: "Gateway Timeout",
headers: new Headers({
"content-type": "text/html",
}),
status: 504,
};
},
};
const handleErrorResponse = (err: Error) => {
const { name, message, cause } = err;
// TODO: remove
log.error(`ERROR - caught this error: ${err}`);
log.error(`ERROR - error name: ${name}`);
log.error(`ERROR - error msg: ${message}`);
log.error(`ERROR - error cause: ${cause}`);
log.error(`ERROR - error all: ${err}`);
switch (true) {
// TODO: remove
case err.cause === "Felt sick":
return smash.badGateway(err);
case err.message === "Status code 404":
return smash.gatewayTimeout(err);
case err.message === "Status code 404 for sitemap.yaml":
return smash.gatewayTimeout(err);
case err.message === "parsedYaml.map is not a function":
return smash.badImplementation(err);
case err.name === "YAMLError":
return smash.badGateway(err);
case err.message === "parsedYamlDocList.map is not a function":
return smash.badGateway(err);
case err.message === "Unexpected end of input":
return smash.badImplementation(err);
case err.message === "Unsupported front matter format":
return smash.badImplementation(err);
case err.message === "Unable to test for unknown front matter format":
return smash.badImplementation(err);
default:
return smash.badImplementation(err);
}
};
export async function serveZettelkasten({
conn,
template = simpleTemplate,
snippet = simpleSnippet,
stylesheetlinks = [],
css = "",
zettelResource,
keyValueStore = "DISABLE",
ttl,
scripttaglinks = [],
}: ServeZettelkastenType) {
// TODO: Throw error if zettelResource is undefined
// This "upgrades" a network connection into an HTTP connection.
const httpConn = Deno.serveHttp(conn);
// Each request sent over the HTTP connection will be yielded as an async
// iterator from the HTTP connection.
// Needed until Deno KV is not longer considered experimental and behind --unstable flag
let kv: Deno.Kv | undefined;
const kvIsEnabled = keyValueStore === "ENABLE";
if (kvIsEnabled) {
kv = await Deno.openKv();
}
for await (const { request, respondWith } of httpConn) {
const { pathname } = new URL(request.url);
const ifNoneMatch = request.headers.get("if-none-match");
if (kvIsEnabled && kv && ttl) {
const { value } = await kv.get<DocMeta>([pathname]);
if (value) {
const { timestamp, etag, body } = value;
const isKVCacheHit = timestamp + ttl > Number(new Date().getTime());
if (ifNoneMatch === etag && isKVCacheHit) {
log.info("Hit Etag in KV");
respondWith(
new Response(null, {
headers: new Headers({}),
status: 304,
}),
);
continue;
}
if (isKVCacheHit) {
log.info("Hit body in KV");
respondWith(
new Response(body, {
headers: new Headers({
"content-type": "text/html",
"etag": etag,
}),
status: 200,
}),
);
continue;
}
}
}
if (pathname === "/") {
log.info("Home route '/' was called");
respondWith(
reply(
ifNoneMatch,
pathname,
kv,
await homeHandler({
template,
snippet,
stylesheetlinks,
css,
resource: zettelResource,
scripttaglinks,
}).catch(handleErrorResponse),
),
).catch((err) => {
// TODO: How to handle this error?
log.critical(`Refreshed too fast...🏎️ : ${err}`);
});
}
if (pathname === "/favicon.ico") {
log.info("Favicon route '/favicon.ico' was called");
// TODO: Deliver favicon
respondWith(
reply(ifNoneMatch, pathname, kv, {
body: "404",
headers: new Headers({
"content-type": "text/html",
}),
status: 404,
}),
).catch((err) => {
log.critical(`Refreshed favicon too fast...🏎️ : ${err}`);
});
}
if (pathname !== "/" && pathname !== "/favicon.ico") {
log.info(`Path route '${pathname}' was called`);
respondWith(
reply(
ifNoneMatch,
pathname,
kv,
await pathHandler({
pathname,
template,
snippet,
stylesheetlinks,
css,
resource: zettelResource,
scripttaglinks,
}).catch(handleErrorResponse),
),
).catch((err) => {
// TODO: How to handle this error?
log.critical(`Refreshed too fast, too furious...🏎️ 🚙 : ${err}`);
});
}
}
}