From 446d7299814b84a94587059846aa7bad9a8feaf0 Mon Sep 17 00:00:00 2001
From: Adam Brown <adampsbrown@gmail.com>
Date: Sat, 29 Oct 2022 11:23:44 +0100
Subject: [PATCH] adding basic list support

---
 .../sync/internal/sync/message/HtmlParser.kt  | 69 ++++++++++++++++++-
 .../internal/sync/RichMessageParserTest.kt    | 21 ++++++
 2 files changed, 87 insertions(+), 3 deletions(-)

diff --git a/matrix/services/sync/src/main/kotlin/app/dapk/st/matrix/sync/internal/sync/message/HtmlParser.kt b/matrix/services/sync/src/main/kotlin/app/dapk/st/matrix/sync/internal/sync/message/HtmlParser.kt
index c7b1ece..b979f66 100644
--- a/matrix/services/sync/src/main/kotlin/app/dapk/st/matrix/sync/internal/sync/message/HtmlParser.kt
+++ b/matrix/services/sync/src/main/kotlin/app/dapk/st/matrix/sync/internal/sync/message/HtmlParser.kt
@@ -5,10 +5,11 @@ import app.dapk.st.matrix.common.UserId
 private const val TAG_OPEN = '<'
 private const val TAG_CLOSE = '>'
 private const val NO_RESULT_FOUND = -1
+private const val LI_VALUE_CAPTURE = "value=\""
 
 internal class HtmlParser {
 
-    fun parseHtmlTags(input: String, searchIndex: Int, builder: PartBuilder) = input.findTag(
+    fun parseHtmlTags(input: String, searchIndex: Int, builder: PartBuilder): SearchIndex = input.findTag(
         fromIndex = searchIndex,
         onInvalidTag = { builder.appendText(input[it].toString()) },
         onTag = { tagOpen, tagClose ->
@@ -59,7 +60,7 @@ internal class HtmlParser {
         wholeTag: String,
         builder: PartBuilder,
         tagContent: String,
-        exitTagCloseIndex: Int
+        exitTagCloseIndex: Int,
     ) = when (tagName) {
         "a" -> {
             val findHrefUrl = wholeTag.substringAfter("href=").replace("\"", "").removeSuffix(">")
@@ -84,6 +85,11 @@ internal class HtmlParser {
             exitTagCloseIndex
         }
 
+        "ul", "ol" -> {
+            parseList(tagName, tagContent, builder)
+            exitTagCloseIndex
+        }
+
         "h1", "h2", "h3", "h4", "h5" -> {
             builder.appendBold(tagContent)
             builder.appendNewline()
@@ -128,8 +134,65 @@ internal class HtmlParser {
         }
     }
 
+    private fun parseList(parentTag: String, parentContent: String, builder: PartBuilder) {
+        var nextIndex = 0
+        var index = 1
+        while (nextIndex != END_SEARCH) {
+            nextIndex = singleTagParser(parentContent, "li", nextIndex, builder) { wholeTag, tagContent ->
+                val content = when (parentTag) {
+                    "ol" -> {
+                        index = wholeTag.indexOf(LI_VALUE_CAPTURE).let {
+                            if (it == -1) {
+                                index
+                            } else {
+                                val start = it + LI_VALUE_CAPTURE.length
+                                wholeTag.substring(start).substringBefore('\"').toInt()
+                            }
+                        }
+
+                        "$index. $tagContent".also {
+                            index++
+                        }
+                    }
+
+                    else -> "- $tagContent"
+                }
+                builder.appendText(content)
+                builder.appendNewline()
+            }
+        }
+    }
+
+
+    private fun singleTagParser(content: String, wantedTagName: String, searchIndex: Int, builder: PartBuilder, onTag: (String, String) -> Unit): SearchIndex {
+        return content.findTag(
+            fromIndex = searchIndex,
+            onInvalidTag = { builder.appendText(content[it].toString()) },
+            onTag = { tagOpen, tagClose ->
+                val wholeTag = content.substring(tagOpen, tagClose + 1)
+                val tagName = wholeTag.substring(1, wholeTag.indexOfFirst { it == '>' || it == ' ' })
+
+                if (tagName == wantedTagName) {
+                    val exitTag = "</$tagName>"
+                    val exitIndex = content.indexOf(exitTag, startIndex = tagClose)
+                    val exitTagCloseIndex = exitIndex + exitTag.length
+                    if (exitIndex == END_SEARCH) {
+                        builder.appendText(content[searchIndex].toString())
+                        searchIndex.next()
+                    } else {
+                        val tagContent = content.substring(tagClose + 1, exitIndex)
+                        onTag(wholeTag, tagContent)
+                        exitTagCloseIndex
+                    }
+                } else {
+                    END_SEARCH
+                }
+            }
+        )
+    }
+
     fun test(startingFrom: Int, intput: String): Int {
-        return intput.indexOf('<', startingFrom)
+        return intput.indexOf(TAG_OPEN, startingFrom)
     }
 
 }
\ No newline at end of file
diff --git a/matrix/services/sync/src/test/kotlin/app/dapk/st/matrix/sync/internal/sync/RichMessageParserTest.kt b/matrix/services/sync/src/test/kotlin/app/dapk/st/matrix/sync/internal/sync/RichMessageParserTest.kt
index 13e8649..5be1d1b 100644
--- a/matrix/services/sync/src/test/kotlin/app/dapk/st/matrix/sync/internal/sync/RichMessageParserTest.kt
+++ b/matrix/services/sync/src/test/kotlin/app/dapk/st/matrix/sync/internal/sync/RichMessageParserTest.kt
@@ -74,6 +74,27 @@ class RichMessageParserTest {
         expected = RichText(setOf(Normal("Hello world!\nnext line\nanother line")))
     )
 
+
+    @Test
+    fun `parses lists`() = runParserTest(
+        Case(
+            input = "<ul><li>content in list item</li><li>another item in list</li></ul>",
+            expected = RichText(setOf(Normal("- content in list item\n- another item in list")))
+        ),
+        Case(
+            input = "<ol><li>content in list item</li><li>another item in list</li></ol>",
+            expected = RichText(setOf(Normal("1. content in list item\n2. another item in list")))
+        ),
+        Case(
+            input = """<ol><li value="5">content in list item</li><li>another item in list</li></ol>""",
+            expected = RichText(setOf(Normal("5. content in list item\n6. another item in list")))
+        ),
+        Case(
+            input = """<ol><li value="3">content in list item</li><li>another item in list</li><li value="10">another change</li><li>without value</li></ol>""",
+            expected = RichText(setOf(Normal("3. content in list item\n4. another item in list\n10. another change\n11. without value")))
+        ),
+    )
+
     @Test
     fun `parses urls`() = runParserTest(
         Case(