From c31a9bf00125588682a20869924fc7b7a5c7d4a1 Mon Sep 17 00:00:00 2001
From: EuAndreh <eu@euandre.org>
Date: Tue, 18 Jan 2022 12:39:05 -0300
Subject: src/td.in: Add optimal_line_for_type()

Use the new function in insert_at_line():  whenever a given line $N is
equal to 0, meaning it doesn't exist yet in the file, the
optimal_line_for_type() will scan the file and answer with the "optimal"
line number that the the type should be inserted at.  It does that by
looking at the order in which types apper in $TD_TYPES, and compare that
with $TD_FILE:

- if a previous type has appeared already, it continues scanning the
  file until a different level 1 heading appears, or until the end of
  the file;
- if a type that comes after appears, it gets inserted before it;
- if no types exist in the file yet, it gets inserted at the end.

It fixes #td-05580844-40db-0db6-b11e-9f041a08c0a7.
---
 src/td.in | 44 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 42 insertions(+), 2 deletions(-)

diff --git a/src/td.in b/src/td.in
index 6f1c516..ecc19c8 100755
--- a/src/td.in
+++ b/src/td.in
@@ -184,6 +184,44 @@ mkdtemp() {
 # Core functions
 #
 
+optimal_line_for_type() {
+	GOAL_TYPE="$1"
+	GOAL_INDEX="$(echo "$TD_TYPES" | awk "/^$GOAL_TYPE:/ { printf NR }")"
+	TYPE_HEADINGS="$(mkstemp)"
+	echo "$TD_TYPES" | cut -d: -f2- | sed 's/^/# /' > "$TYPE_HEADINGS"
+	IN_TD_SECTION=false
+	IN_TD_ENTRY=false
+	LINE_NUMBER=0
+	LAST_MATCH=0
+	IN_TD_REGION=false
+	while read -r line; do
+		LINE_NUMBER=$((LINE_NUMBER + 1))
+		if ! echo "$line" | grep -Eq '^# .+$'; then
+			continue
+		fi
+		MATCH="$(grep -nF "$line" "$TYPE_HEADINGS" ||:)"
+		if [ -n "$MATCH" ]; then
+			MATCH_N="$(echo "$MATCH" | cut -d: -f1)"
+			MATCH_LINE="$(echo "$MATCH" | cut -d: -f2-)"
+			if [ "$line" = "$MATCH_LINE" ]; then
+				IN_TD_REGION=true
+				if [ "$MATCH_N" -lt "$GOAL_INDEX" ]; then
+					LAST_MATCH="$MATCH_N"
+				else
+					echo $((LINE_NUMBER - 1))
+					return
+				fi
+			fi
+		elif [ "$IN_TD_REGION" = true ]; then
+			echo $((LINE_NUMBER - 1))
+			echo uhu >&2
+			return
+		fi
+	done < "$TD_FILE"
+	echo "chegou" >&2
+	echo $((LINE_NUMBER))
+}
+
 insert_at_line() {
 	N="$1"
 	F="$2"
@@ -194,10 +232,12 @@ insert_at_line() {
 		printf "$MSG_FILE_DOESNT_EXIST_CREATING\n" "$TD_FILE" >&2
 		cat - > "$TMPF"
 	elif [ "$N" = 0 ]; then
+		DESIRED_N="$(optimal_line_for_type "$TYPE")"
 		printf "$MSG_TYPE_DOESNT_EXIST_CREATING\n" "$TYPE" >&2
-		printf '%s\n\n\n%s\n' \
+		printf '%s\n\n\n%s\n\n\n%s\n' \
+			"$(head -n "$DESIRED_N" "$F")" \
 			"$(cat -)" \
-			"$(cat "$F")" \
+			"$(tail -n +$((DESIRED_N+1)) "$F")" \
 			> "$TMPF"
 	else
 		printf '%s\n\n%s\n\n%s\n' \
-- 
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