#!/usr/bin/env bash
set -euo pipefail

# Render top-down preview PNGs for any STL in gridfinity-bin-label/labels/
# that does not yet have a sibling .png. Parameters (text + symbols) are
# derived from the STL filename and rendered through the 2D-silhouette
# helper at gridfinity-bin-label/examples/render.scad so the output
# matches the original M2-M5 preview style.

REPO_DIR="$(cd "$(dirname "$0")/.." && pwd)"
LABELS_DIR="${REPO_DIR}/gridfinity-bin-label/labels"
RENDER_SCAD="${REPO_DIR}/gridfinity-bin-label/examples/render.scad"

if ! command -v openscad &>/dev/null; then
    echo "Error: openscad not found in PATH" >&2
    exit 1
fi

# Top-down ortho view centered on the label. Camera distance and image
# aspect were tuned so the label nearly fills the frame with roughly
# equal margins on all four sides.
CAMERA="18,5.5,0.4,0,0,0,45"
IMGSIZE="960,360"

# Map a label filename stem (e.g. "M3x16", "M4_washer", "M2_nut_washer", "M5")
# to text + symbol parameters for examples/render.scad. Echoes one -D
# override per line; returns 1 if the filename is not recognized.
derive_params() {
    local stem="$1"

    if [[ "$stem" =~ ^M([0-9]+)x([0-9]+)$ ]]; then
        printf 'example_text=%s\n' "\"M${BASH_REMATCH[1]}*${BASH_REMATCH[2]}\""
        printf 'example_symbol1=%s\n' '"side_pan"'
        printf 'example_symbol2=%s\n' '"bit_hex"'
    elif [[ "$stem" =~ ^M([0-9]+)_nut_washer$ ]]; then
        printf 'example_text=%s\n' "\"M${BASH_REMATCH[1]}\""
        printf 'example_symbol1=%s\n' '"washer"'
        printf 'example_symbol2=%s\n' '"nut"'
        # Original nut+washer renders bumped the left icon inward 1 mm.
        printf 'sym1_pad=%s\n' '2'
    elif [[ "$stem" =~ ^M([0-9]+)_washer$ ]]; then
        printf 'example_text=%s\n' "\"M${BASH_REMATCH[1]}\""
        printf 'example_symbol1=%s\n' '"none"'
        printf 'example_symbol2=%s\n' '"washer"'
    elif [[ "$stem" =~ ^M([0-9]+)$ ]]; then
        printf 'example_text=%s\n' "\"M${BASH_REMATCH[1]}\""
        printf 'example_symbol1=%s\n' '"none"'
        printf 'example_symbol2=%s\n' '"bit_hex"'
    else
        return 1
    fi
}

count=0
skipped=0
unmatched=0
for stl in "$LABELS_DIR"/*.stl; do
    [[ -e "$stl" ]] || continue
    stem="$(basename "$stl" .stl)"
    png="${LABELS_DIR}/${stem}.png"

    if [[ -e "$png" ]]; then
        skipped=$((skipped + 1))
        continue
    fi

    mapfile -t params < <(derive_params "$stem") || true
    if [[ ${#params[@]} -eq 0 ]]; then
        echo "Skipping ${stem}: no parameter mapping for this filename" >&2
        unmatched=$((unmatched + 1))
        continue
    fi

    args=()
    for p in "${params[@]}"; do
        args+=( -D "$p" )
    done

    echo "Rendering ${stem}.png"
    openscad "${args[@]}" \
        --render \
        --camera="$CAMERA" \
        --projection=ortho \
        --imgsize="$IMGSIZE" \
        -o "$png" \
        "$RENDER_SCAD" >/dev/null 2>&1
    count=$((count + 1))
done

echo "Generated ${count} preview(s); skipped ${skipped} existing, ${unmatched} unmatched."