From 890e80854f97881b1d690991c7dccb6d67fb887a Mon Sep 17 00:00:00 2001
From: Cadence Ember <cadence@disroot.org>
Date: Mon, 9 Jun 2025 12:07:11 +1200
Subject: [PATCH] m->d: render tables

---
 src/m2d/converters/event-to-message.js      | 21 ++++++++++++
 src/m2d/converters/event-to-message.test.js | 36 +++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/src/m2d/converters/event-to-message.js b/src/m2d/converters/event-to-message.js
index 7044859..4f834b7 100644
--- a/src/m2d/converters/event-to-message.js
+++ b/src/m2d/converters/event-to-message.js
@@ -154,6 +154,27 @@ turndownService.addRule("listItem", {
 	}
 })
 
+turndownService.addRule("table", {
+	filter: "table",
+	replacement: function (content, node, options) {
+		const trs = node.querySelectorAll("tr").cache
+		/** @type {{text: string, tag: string}[][]} */
+		const tableText = trs.map(tr => [...tr.querySelectorAll("th, td")].map(cell => ({text: cell.textContent, tag: cell.tagName})))
+		const tableTextByColumn = tableText[0].map((col, i) => tableText.map(row => row[i]))
+		const columnWidths = tableTextByColumn.map(col => Math.max(...col.map(cell => cell.text.length)))
+		const resultRows = tableText.map((row, rowIndex) =>
+			row.map((cell, colIndex) =>
+				cell.text.padEnd(columnWidths[colIndex])
+			).join("  ")
+		)
+		const tableHasHeader = tableText[0].slice(1).some(cell => cell.tag === "TH")
+		if (tableHasHeader) {
+			resultRows.splice(1, 0, "-".repeat(columnWidths.reduce((a, c) => a + c + 2)))
+		}
+		return "```\n" + resultRows.join("\n") + "```"
+	}
+})
+
 /** @type {string[]} SPRITE SHEET EMOJIS FEATURE: mxc urls for the currently processing message */
 let endOfMessageEmojis = []
 turndownService.addRule("emoji", {
diff --git a/src/m2d/converters/event-to-message.test.js b/src/m2d/converters/event-to-message.test.js
index 4c1ff6c..70853aa 100644
--- a/src/m2d/converters/event-to-message.test.js
+++ b/src/m2d/converters/event-to-message.test.js
@@ -4537,6 +4537,42 @@ test("event2message: @room in the middle of a link is not converted", async t =>
 	)
 })
 
+test("event2message: table", async t => {
+	t.deepEqual(
+		await eventToMessage({
+			type: "m.room.message",
+			sender: "@cadence:cadence.moe",
+			content: {
+				msgtype: "m.text",
+				body: "wrong body",
+				format: "org.matrix.custom.html",
+				formatted_body: "content<table><thead><tr><th>Col 1</th><th>Col 2</th><th>Col 3</th></tr></thead><tbody><tr><th>Apple</th><td>Banana</td><td>Cherry</td></tr><tr><th>Aardvark</th><td>Bee</td><td>Crocodile</td></tr><tr><td>Argon</td><td>Boron</td><td>Carbon</td></tr></tbody></table>more content"
+			},
+			room_id: "!kLRqKKUQXcibIMtOpl:cadence.moe",
+			event_id: "$SiXetU9h9Dg-M9Frcw_C6ahnoXZ3QPZe3MVJR5tcB9A"
+		}),
+		{
+			messagesToDelete: [],
+			messagesToEdit: [],
+			messagesToSend: [{
+				username: "cadence [they]",
+				content: "content```"
+				+ "\nCol 1     Col 2   Col 3  "
+				+ "\n---------------------------"
+				+ "\nApple     Banana  Cherry "
+				+ "\nAardvark  Bee     Crocodile"
+				+ "\nArgon     Boron   Carbon   ```"
+				+ "more content",
+				avatar_url: undefined,
+				allowed_mentions: {
+					parse: ["users", "roles"]
+				}
+			}],
+			ensureJoined: []
+		}
+	)
+})
+
 slow()("event2message: unknown emoji at the end is reuploaded as a sprite sheet", async t => {
 	const messages = await eventToMessage({
 		type: "m.room.message",