1 files changed, 233 insertions, 0 deletions
diff --git a/buffer.c b/buffer.c
new file mode 100644
index 0000000..f82e553
--- /dev/null
+++ b/buffer.c
@@ -0,0 +1,233 @@
+/* Copyright (C) 2020  June McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * Additional permission under GNU GPL version 3 section 7:
+ *
+ * If you modify this Program, or any covered work, by linking or
+ * combining it with OpenSSL (or a modified version of that library),
+ * containing parts covered by the terms of the OpenSSL License and the
+ * original SSLeay license, the licensors of this Program grant you
+ * additional permission to convey the resulting work. Corresponding
+ * Source for a non-source form of such a combination shall include the
+ * source code for the parts of OpenSSL used as well as that of the
+ * covered work.
+ */
+
+#include <err.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sysexits.h>
+#include <time.h>
+#include <wchar.h>
+#include <wctype.h>
+
+#include "chat.h"
+
+struct Lines {
+	size_t len;
+	struct Line lines[BufferCap];
+};
+_Static_assert(!(BufferCap & (BufferCap - 1)), "BufferCap is power of two");
+
+struct Buffer {
+	struct Lines soft;
+	struct Lines hard;
+};
+
+struct Buffer *bufferAlloc(void) {
+	struct Buffer *buffer = calloc(1, sizeof(*buffer));
+	if (!buffer) err(EX_OSERR, "calloc");
+	return buffer;
+}
+
+void bufferFree(struct Buffer *buffer) {
+	for (size_t i = 0; i < BufferCap; ++i) {
+		free(buffer->soft.lines[i].str);
+		free(buffer->hard.lines[i].str);
+	}
+	free(buffer);
+}
+
+static const struct Line *linesLine(const struct Lines *lines, size_t i) {
+	const struct Line *line = &lines->lines[(lines->len + i) % BufferCap];
+	return (line->str ? line : NULL);
+}
+
+static struct Line *linesNext(struct Lines *lines) {
+	struct Line *line = &lines->lines[lines->len++ % BufferCap];
+	free(line->str);
+	return line;
+}
+
+const struct Line *bufferSoft(const struct Buffer *buffer, size_t i) {
+	return linesLine(&buffer->soft, i);
+}
+
+const struct Line *bufferHard(const struct Buffer *buffer, size_t i) {
+	return linesLine(&buffer->hard, i);
+}
+
+enum { StyleCap = 10 };
+static char *styleCopy(char *ptr, char *end, struct Style style) {
+	ptr = seprintf(
+		ptr, end, "%s%s%s%s",
+		(style.attr & Bold ? (const char []) { B, '\0' } : ""),
+		(style.attr & Reverse ? (const char []) { R, '\0' } : ""),
+		(style.attr & Italic ? (const char []) { I, '\0' } : ""),
+		(style.attr & Underline ? (const char []) { U, '\0' } : "")
+	);
+	if (style.fg != Default || style.bg != Default) {
+		ptr = seprintf(ptr, end, "\3%02d,%02d", style.fg, style.bg);
+	}
+	return ptr;
+}
+
+static const wchar_t ZWS = L'\u200B';
+static const wchar_t ZWNJ = L'\u200C';
+
+static int flow(struct Lines *hard, int cols, const struct Line *soft) {
+	int flowed = 1;
+
+	struct Line *line = linesNext(hard);
+	line->num = soft->num;
+	line->heat = soft->heat;
+	line->time = soft->time;
+	line->str = strdup(soft->str);
+	if (!line->str) err(EX_OSERR, "strdup");
+
+	int width = 0;
+	int align = 0;
+	char *wrap = NULL;
+	struct Style style = StyleDefault;
+	struct Style wrapStyle = StyleDefault;
+	for (char *str = line->str; *str;) {
+		size_t len = styleParse(&style, (const char **)&str);
+		if (!len) continue;
+
+		bool tab = (*str == '\t' && !align);
+		if (tab) *str = ' ';
+
+		wchar_t wc = L'\0';
+		int n = mbtowc(&wc, str, len);
+		if (n < 0) {
+			n = 1;
+			// ncurses will render these as "~A".
+			width += (*str & '\200' ? 2 : 1);
+		} else if (wc == ZWS || wc == ZWNJ) {
+			// ncurses likes to render these as spaces when they should be
+			// zero-width, so just remove them entirely.
+			memmove(str, &str[n], strlen(&str[n]) + 1);
+			continue;
+		} else if (wc == L'\t') {
+			// Assuming TABSIZE = 8.
+			width += 8 - (width % 8);
+		} else if (wc < L' ' || wc == L'\177') {
+			// ncurses will render these as "^A".
+			width += 2;
+		} else if (wcwidth(wc) > 0) {
+			width += wcwidth(wc);
+		}
+
+		if (tab && width < cols) {
+			align = width;
+			wrap = NULL;
+		}
+		if (iswspace(wc) && !tab) {
+			wrap = str;
+			wrapStyle = style;
+		}
+		if (wc == L'-' && width <= cols) {
+			wrap = &str[n];
+			wrapStyle = style;
+		}
+
+		if (width <= cols) {
+			str += n;
+			continue;
+		} else if (!wrap) {
+			wrap = str;
+			wrapStyle = style;
+		}
+
+		n = 0;
+		len = strlen(wrap);
+		for (int m; wrap[n] && (m = mbtowc(&wc, &wrap[n], len - n)); n += m) {
+			if (m < 0) {
+				m = 1;
+			} else if (!iswspace(wc)) {
+				break;
+			}
+		}
+		if (!wrap[n]) {
+			*wrap = '\0';
+			break;
+		}
+
+		flowed++;
+		line = linesNext(hard);
+		line->num = soft->num;
+		line->heat = soft->heat;
+		line->time = 0;
+
+		size_t cap = StyleCap + align + strlen(&wrap[n]) + 1;
+		line->str = malloc(cap);
+		if (!line->str) err(EX_OSERR, "malloc");
+
+		char *end = &line->str[cap];
+		str = seprintf(line->str, end, "%*s", (width = align), "");
+		str = styleCopy(str, end, wrapStyle);
+		style = wrapStyle;
+		seprintf(str, end, "%s", &wrap[n]);
+
+		*wrap = '\0';
+		wrap = NULL;
+	}
+
+	return flowed;
+}
+
+int bufferPush(
+	struct Buffer *buffer, int cols, enum Heat thresh,
+	enum Heat heat, time_t time, const char *str
+) {
+	struct Line *soft = linesNext(&buffer->soft);
+	soft->num = buffer->soft.len;
+	soft->heat = heat;
+	soft->time = time;
+	soft->str = strdup(str);
+	if (!soft->str) err(EX_OSERR, "strdup");
+	if (heat < thresh) return 0;
+	return flow(&buffer->hard, cols, soft);
+}
+
+int
+bufferReflow(struct Buffer *buffer, int cols, enum Heat thresh, size_t tail) {
+	buffer->hard.len = 0;
+	for (size_t i = 0; i < BufferCap; ++i) {
+		free(buffer->hard.lines[i].str);
+		buffer->hard.lines[i].str = NULL;
+	}
+	int flowed = 0;
+	for (size_t i = 0; i < BufferCap; ++i) {
+		const struct Line *soft = bufferSoft(buffer, i);
+		if (!soft) continue;
+		if (soft->heat < thresh) continue;
+		int n = flow(&buffer->hard, cols, soft);
+		if (i >= BufferCap - tail) flowed += n;
+	}
+	return flowed;
+}