Fix full last-page view redirect wrap-around

3 files changed, 96 insertions, 41 deletions

diff --git a/bin/photoalbum b/bin/photoalbum
index ef15194..15bc253 100755
--- a/bin/photoalbum
+++ b/bin/photoalbum
@@ -1213,13 +1213,31 @@ render_photo_view_and_details() {
 
 render_view_redirects() {
     local -r html_dir="$1"; shift
+    local -i max_page=0
+    local -a prefixes=()
     local lastview
     local nextredirect
     local page
-    local prefix
     local prevredirect
+    local prefix
+
+    mapfile -t prefixes < <(
+        find "$DIST_DIR/$html_dir" \
+            -maxdepth 1 \
+            -regextype posix-egrep \
+            -regex '.*/[0-9]+-[0-9]+\.html' \
+            -printf '%f\n' \
+            | cut -d'-' -f1 \
+            | sort -n -u
+    )
+
+    if (( ${#prefixes[@]} == 0 )); then
+        return
+    fi
+
+    max_page=${prefixes[$(( ${#prefixes[@]} - 1 ))]}
 
-    while IFS= read -r prefix; do
+    for prefix in "${prefixes[@]}"; do
         page="$prefix"
         lastview=$(last_view_number "$page" "$html_dir")
 
@@ -1230,27 +1248,19 @@ render_view_redirects() {
             html_dir "$html_dir" \
             redirect_page "$(( page - 1 ))-${MAXPREVIEWS}"
 
-        if (( lastview == MAXPREVIEWS )); then
-            template redirect "$nextredirect.html" \
-                html_dir "$html_dir" \
-                redirect_page "$(( page + 1 ))-1"
-        else
+        if (( page == max_page )); then
             template redirect "0-$MAXPREVIEWS.html" \
                 html_dir "$html_dir" \
                 redirect_page "${page}-$lastview"
             template redirect "$nextredirect.html" \
                 html_dir "$html_dir" \
                 redirect_page '1-1'
+        else
+            template redirect "$nextredirect.html" \
+                html_dir "$html_dir" \
+                redirect_page "$(( page + 1 ))-1"
         fi
-    done < <(
-        find "$DIST_DIR/$html_dir" \
-            -maxdepth 1 \
-            -regextype posix-egrep \
-            -regex '.*/[0-9]+-[0-9]+\.html' \
-            -printf '%f\n' \
-            | cut -d'-' -f1 \
-            | sort -u
-    )
+    done
 }
 
 render_album_index_redirect() {
@@ -1609,10 +1619,7 @@ dry_run() {
     if (( image_count > 0 )); then
         details_count=$image_count
         page_count=$(( (image_count + MAXPREVIEWS - 1) / MAXPREVIEWS ))
-        redirect_count=$(( page_count * 2 ))
-        if (( image_count % MAXPREVIEWS != 0 )); then
-            (( ++redirect_count ))
-        fi
+        redirect_count=$(( page_count * 2 + 1 ))
     fi
 
     printf 'Dry run: no files will be written.\n'
diff --git a/src/photoalbum.sh b/src/photoalbum.sh
index 7d75d1c..965dd27 100755
--- a/src/photoalbum.sh
+++ b/src/photoalbum.sh
@@ -1213,13 +1213,31 @@ render_photo_view_and_details() {
 
 render_view_redirects() {
     local -r html_dir="$1"; shift
+    local -i max_page=0
+    local -a prefixes=()
     local lastview
     local nextredirect
     local page
-    local prefix
     local prevredirect
+    local prefix
+
+    mapfile -t prefixes < <(
+        find "$DIST_DIR/$html_dir" \
+            -maxdepth 1 \
+            -regextype posix-egrep \
+            -regex '.*/[0-9]+-[0-9]+\.html' \
+            -printf '%f\n' \
+            | cut -d'-' -f1 \
+            | sort -n -u
+    )
+
+    if (( ${#prefixes[@]} == 0 )); then
+        return
+    fi
+
+    max_page=${prefixes[$(( ${#prefixes[@]} - 1 ))]}
 
-    while IFS= read -r prefix; do
+    for prefix in "${prefixes[@]}"; do
         page="$prefix"
         lastview=$(last_view_number "$page" "$html_dir")
 
@@ -1230,27 +1248,19 @@ render_view_redirects() {
             html_dir "$html_dir" \
             redirect_page "$(( page - 1 ))-${MAXPREVIEWS}"
 
-        if (( lastview == MAXPREVIEWS )); then
-            template redirect "$nextredirect.html" \
-                html_dir "$html_dir" \
-                redirect_page "$(( page + 1 ))-1"
-        else
+        if (( page == max_page )); then
             template redirect "0-$MAXPREVIEWS.html" \
                 html_dir "$html_dir" \
                 redirect_page "${page}-$lastview"
             template redirect "$nextredirect.html" \
                 html_dir "$html_dir" \
                 redirect_page '1-1'
+        else
+            template redirect "$nextredirect.html" \
+                html_dir "$html_dir" \
+                redirect_page "$(( page + 1 ))-1"
         fi
-    done < <(
-        find "$DIST_DIR/$html_dir" \
-            -maxdepth 1 \
-            -regextype posix-egrep \
-            -regex '.*/[0-9]+-[0-9]+\.html' \
-            -printf '%f\n' \
-            | cut -d'-' -f1 \
-            | sort -u
-    )
+    done
 }
 
 render_album_index_redirect() {
@@ -1609,10 +1619,7 @@ dry_run() {
     if (( image_count > 0 )); then
         details_count=$image_count
         page_count=$(( (image_count + MAXPREVIEWS - 1) / MAXPREVIEWS ))
-        redirect_count=$(( page_count * 2 ))
-        if (( image_count % MAXPREVIEWS != 0 )); then
-            (( ++redirect_count ))
-        fi
+        redirect_count=$(( page_count * 2 + 1 ))
     fi
 
     printf 'Dry run: no files will be written.\n'
diff --git a/tests/cli.sh b/tests/cli.sh
index b58610c..e4a94a6 100755
--- a/tests/cli.sh
+++ b/tests/cli.sh
@@ -1388,7 +1388,7 @@ test_dry_run_reports_cli_overrides_without_writes() {
         "  $dist_dir/[page]-[image]-details.html (6 details pages)" \
         "$output"
     test::assert_contains \
-        "  $dist_dir/[redirect].html (6 navigation redirects)" \
+        "  $dist_dir/[redirect].html (7 navigation redirects)" \
         "$output"
     test::assert_not_contains "$dist_dir/html" "$output"
     test::assert_contains "  $dist_dir/incoming-<timestamp>.tar" "$output"
@@ -1945,6 +1945,44 @@ test_render_view_redirects_uses_numeric_last_view() {
     test::teardown
 }
 
+test_render_view_redirects_wraps_when_last_page_full() {
+    local dist_dir
+    local html_dir
+    local next_redirect_html
+    local prev_redirect_html
+    local view
+
+    test::setup
+    dist_dir="$TEST_TMPDIR/dist"
+    html_dir='.'
+    mkdir -p "$dist_dir"
+
+    # shellcheck source=/dev/null
+    source <(sed '$d' "$TEST_PHOTOALBUM")
+
+    export DIST_DIR="$dist_dir"
+    export TEMPLATE_DIR="$TEST_REPO_ROOT/share/templates/default"
+    export PHOTOALBUM_OUTPUT_MODE=quiet
+    export MAXPREVIEWS=2
+
+    for view in 1 2; do
+        : > "$dist_dir/1-$view.html"
+        : > "$dist_dir/2-$view.html"
+        : > "$dist_dir/3-$view.html"
+    done
+
+    render_view_redirects "$html_dir"
+
+    test::assert_file_exists "$dist_dir/0-2.html"
+    test::assert_file_exists "$dist_dir/3-3.html"
+    prev_redirect_html=$(<"$dist_dir/0-2.html")
+    next_redirect_html=$(<"$dist_dir/3-3.html")
+    test::assert_contains 'url=3-2.html' "$prev_redirect_html"
+    test::assert_contains 'url=1-1.html' "$next_redirect_html"
+    test::assert_path_absent "$dist_dir/4-1.html"
+    test::teardown
+}
+
 test_generate_config_no_splash_keeps_index_redirect() {
     local config_file
     local fake_bin
@@ -2808,6 +2846,9 @@ main() {
         'view redirects use numeric last view' \
         test_render_view_redirects_uses_numeric_last_view
     test::run_case \
+        'view redirects wrap when last page is full' \
+        test_render_view_redirects_wraps_when_last_page_full
+    test::run_case \
         '--generate SPLASH_PAGE=no keeps root index redirect' \
         test_generate_config_no_splash_keeps_index_redirect
     test::run_case \