From 6248b63041d8d5e8ae5b15fe58ccde897b3cfb6e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Tue, 23 Aug 2022 18:52:54 +0200
Subject: Refactor HTML retrieval and parsing.

---
 c/data.cpp | 67 ++++++++++++++++++++++++++++++++++----------------------------
 c/main.cpp |  2 ++
 2 files changed, 39 insertions(+), 30 deletions(-)

diff --git a/c/data.cpp b/c/data.cpp
index 149d9b6..7c0fcb7 100644
--- a/c/data.cpp
+++ b/c/data.cpp
@@ -20,13 +20,42 @@ struct XmlError : public std::exception
 	}
 };
 
-using HtmlParserCtxtPtr = Managed<htmlParserCtxtPtr, xmlFreeParserCtxt, XmlError>;
-using HtmlDocPtr = Managed<htmlDocPtr, xmlFreeDoc, XmlError>;
 using XmlXPathContextPtr = Managed<xmlXPathContextPtr, xmlXPathFreeContext, XmlError>;
 using XmlXPathObjectPtr = Managed<xmlXPathObjectPtr, xmlXPathFreeObject, XmlError>;
 static inline void XmlFree(void* p) { xmlFree(p); }
 using XmlCharPtr = Managed<xmlChar*, XmlFree, XmlError>;
 
+struct ParsedDoc
+{
+	using InternetHandle = Managed<HINTERNET, InternetCloseHandle, InternetError>;
+	using HtmlParserCtxtPtr = Managed<htmlParserCtxtPtr, xmlFreeParserCtxt, XmlError>;
+	using HtmlDocPtr = Managed<htmlDocPtr, xmlFreeDoc, XmlError>;
+
+	InternetHandle hi;
+	InternetHandle hiUrl;
+	HtmlParserCtxtPtr ctxt;
+	char buf[1024];
+
+	ParsedDoc(const wchar_t* wszUrl, const char* szUrl)
+		: hi(InternetOpen(L"Episode Browser", INTERNET_OPEN_TYPE_DIRECT, nullptr, nullptr, 0)),
+		  hiUrl(InternetOpenUrl(hi, wszUrl, nullptr, 0, INTERNET_FLAG_NO_UI, 0)),
+		  ctxt(htmlCreatePushParserCtxt(nullptr, nullptr, buf, sizeof(buf), szUrl, XML_CHAR_ENCODING_UTF8))
+	{
+		htmlCtxtUseOptions(ctxt, HTML_PARSE_RECOVER|HTML_PARSE_NOERROR|HTML_PARSE_NOWARNING);
+
+		BOOL r;
+		DWORD cbRead;
+		while (r = InternetReadFile(hiUrl, buf, sizeof(buf), &cbRead), cbRead) {
+			if (!r)
+				throw InternetError();
+			if (!htmlParseChunk(ctxt, buf, cbRead, 0))
+				throw XmlError();
+		}
+		htmlParseChunk(ctxt, buf, 0, 1); /* Stop parsing. */
+	}
+
+	operator htmlDocPtr() { return ctxt->myDoc; }
+};
 template <size_t N>
 bool WcharsFromXmlchars(wchar_t (&dst)[N], XmlCharPtr utf8) noexcept
 {
@@ -54,37 +83,15 @@ bool WcharsFromXmlchars(wchar_t (&dst)[N], XmlCharPtr utf8) noexcept
 
 void FetchData()
 {
-	LIBXML_TEST_VERSION;
-	using InternetHandle = Managed<HINTERNET, InternetCloseHandle, InternetError>;
-
 	/* The remote data is retrieved using WinINet from the
 	 * Detective Conan World wiki. Using libxml2's "push parser",
-	 * the HTML is parsed piece by piece as it is retrieved. */
-
-	InternetHandle hi = InternetOpen(L"Episode Browser", INTERNET_OPEN_TYPE_DIRECT, nullptr, nullptr, 0);
-	InternetHandle hiUrl = InternetOpenUrl(hi, L"https://www.detectiveconanworld.com/wiki/Anime",
-		    nullptr, 0, INTERNET_FLAG_NO_UI, 0); //L"file://C:/Users/John/Desktop/dcw.html"
-
-	char buf[1024];
-	HtmlParserCtxtPtr ctxt = htmlCreatePushParserCtxt(nullptr, nullptr,
-	    buf, sizeof(buf), "https://www.detectiveconanworld.com/wiki/Anime",
-	    XML_CHAR_ENCODING_UTF8);
-	htmlCtxtUseOptions(ctxt, HTML_PARSE_RECOVER|HTML_PARSE_NOERROR|HTML_PARSE_NOWARNING);
-
-	BOOL r;
-	DWORD cbRead;
-	while (r = InternetReadFile(hiUrl, buf, sizeof(buf), &cbRead), cbRead) {
-		if (!r)
-			throw InternetError();
-		if (!htmlParseChunk(ctxt, buf, cbRead, 0))
-			throw std::runtime_error(xmlGetLastError()->message);
-	}
-	htmlParseChunk(ctxt, buf, 0, 1); /* Stop parsing. */
+	 * the HTML is parsed piece by piece as it is retrieved. The
+	 * episode data are contained in table rows matching a (very!)
+	 * specific XPath query. This is fragile theoretically, but
+	 * unlikely to break practically. */
 
-	/* The episode data are contained in table rows matching a
-	 * (very!) specific XPath query. This is fragile
-	 * theoretically, but unlikely to break practically. */
-	HtmlDocPtr doc = ctxt->myDoc;
+	ParsedDoc doc(L"https://www.detectiveconanworld.com/wiki/Anime",
+	    "https://www.detectiveconanworld.com/wiki/Anime");
 	XmlXPathContextPtr xpathCtx = xmlXPathNewContext(doc);
 	XmlXPathObjectPtr xpathObj = xmlXPathEvalExpression(
 	    reinterpret_cast<const xmlChar*>("//tr[./td[1] != '' and ./td[3][@style='background:#f2fde9;']]"),
diff --git a/c/main.cpp b/c/main.cpp
index 8dc5eab..771b323 100644
--- a/c/main.cpp
+++ b/c/main.cpp
@@ -4,6 +4,7 @@
 #include <windows.h>
 #include <commctrl.h>
 #include <SWI-Prolog.h>
+#include <libxml/xmlversion.h>
 
 #include "debug.h"
 #include "resource.h"
@@ -86,6 +87,7 @@ static void UpdateTheme();
 int WINAPI WinMain(const HINSTANCE hInstance, const HINSTANCE, char* const, const int nCmdShow)
 {
 	setbuf(stdout, nullptr);
+	LIBXML_TEST_VERSION;
 
 	/* Initialize Prolog. */
 	const char* argv[] = {"EpisodeBrowser", nullptr};
-- 
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