#!/bin/sh

# Path to your .bib file
BIBFILE="assets/library.bib"

# Step 1: Extract all citation keys from the .bib file
# This assumes keys follow immediately after @...{KEY,
bibkeys=$(grep -oP '^@\w+\{\K[^,]+' "$BIBFILE")

# Step 2: Initialize array for unused keys
unused=()

for key in $bibkeys; do
    if ! grep -qr "$key" . --include="*.qmd"; then
        unused+=("$key")
    fi
done

if [ ${#unused[@]} -eq 0 ]; then
    echo "All citation keys are used."
else
    echo "Unused citation keys:"
    for key in "${unused[@]}"; do
        echo "  $key"
    done
fi

# Step 5: Optional removal
if [ ${#unused[@]} -gt 0 ]; then
    echo "Removing unused entries from $BIBFILE..."

    awk -v keys="${unused[*]}" '
        BEGIN {
            split(keys, klist);
            for (i in klist) unused[klist[i]] = 1;
            skip = 0;
        }
        /^[[:space:]]*@/ {
            match($0, /^@\w+\{([^,]+),/, m);
            if (m[1] && unused[m[1]]) {
                skip = 1;
                next;
            }
        }
        skip && /^\s*}/ {
            skip = 0;
            next;
        }
        !skip
    ' "$BIBFILE" > "$BIBFILE.tmp" && mv "$BIBFILE.tmp" "$BIBFILE"

    echo "Done."
fi