#!/usr/bin/env bash
# Usage: scripts/view [file.mmd] [-- extra cargo run args...]
#        cat file.mmd | scripts/view [-- extra cargo run args...]
#
# Defaults: -f svg --edge-preset step
# Override any default by passing it explicitly after --
# Set MMDFLUX_VIEW_RENDERER=chafa or MMDFLUX_VIEW_RENDERER=kitty to force a renderer.
# Otherwise the script prefers chafa when installed, then falls back to kitten+rsvg-convert.
#
# Examples:
#   scripts/view tests/fixtures/flowchart/simple.mmd
#   scripts/view tests/fixtures/flowchart/simple.mmd -- --edge-preset basis
#   cat file.mmd | scripts/view

set -euo pipefail

# Keep view as the dev entrypoint, but let the CLI own terminal theme probing so
# the rendering contract stays in one place.
MMD_FORMAT_DEFAULT=(--format svg)
MMD_EDGE_PRESET_DEFAULT=(--edge-preset step)
MMD_THEME_DEFAULT=(--svg-theme-auto)

# Split args: optional file, then optional -- extra-flags
FILE=""
EXTRA_ARGS=()

if [[ $# -gt 0 && "$1" != "--" && -f "$1" ]]; then
    FILE="$1"
    shift
fi

if [[ $# -gt 0 && "$1" == "--" ]]; then
    shift
    EXTRA_ARGS=("$@")
fi

VIEW_RENDERER="${MMDFLUX_VIEW_RENDERER:-auto}"

MERGED_ARGS=()

has_any_flag() {
    local needle
    for needle in "$@"; do
        for extra in "${EXTRA_ARGS[@]+"${EXTRA_ARGS[@]}"}"; do
            if [[ "$extra" == "$needle" || "$extra" == "$needle="* ]]; then
                return 0
            fi
        done
    done
    return 1
}

if ! has_any_flag -f --format; then
    MERGED_ARGS+=("${MMD_FORMAT_DEFAULT[@]}")
fi

if ! has_any_flag --edge-preset; then
    MERGED_ARGS+=("${MMD_EDGE_PRESET_DEFAULT[@]}")
fi

if ! has_any_flag --svg-theme --svg-theme-auto; then
    MERGED_ARGS+=("${MMD_THEME_DEFAULT[@]}")
fi

# Run the pipeline
if [[ -n "$FILE" ]]; then
    INPUT_CMD=(cat "$FILE")
else
    INPUT_CMD=(cat)
fi

kitty_target_raster_size() {
    local window_size width height target_width target_height
    window_size="$(kitten icat --print-window-size 2>/dev/null || true)"
    width="${window_size%%x*}"
    height="${window_size##*x}"

    if [[ "$width" =~ ^[0-9]+$ ]] && [[ "$height" =~ ^[0-9]+$ ]] && (( width > 0 )) && (( height > 0 )); then
        # Oversample to give icat a denser raster to downscale. Cap the raster
        # size so very large HiDPI displays do not create excessive images.
        target_width=$(( width * 2 ))
        target_height=$(( height * 2 ))
        if (( target_width > 4096 )); then
            target_width=4096
        fi
        if (( target_height > 4096 )); then
            target_height=4096
        fi

        printf '%s %s\n' "$target_width" "$target_height"
        return 0
    fi

    return 1
}

command_exists() {
    command -v "$1" >/dev/null 2>&1
}

resolve_view_renderer() {
    case "$VIEW_RENDERER" in
        auto)
            if command_exists chafa; then
                printf '%s\n' chafa
            elif command_exists kitten && command_exists rsvg-convert; then
                printf '%s\n' kitty
            else
                echo "scripts/view: no supported renderer found; install chafa or both kitten and rsvg-convert" >&2
                exit 1
            fi
            ;;
        chafa)
            if ! command_exists chafa; then
                echo "scripts/view: MMDFLUX_VIEW_RENDERER=chafa requires chafa to be installed" >&2
                exit 1
            fi
            printf '%s\n' chafa
            ;;
        kitty)
            if ! command_exists kitten || ! command_exists rsvg-convert; then
                echo "scripts/view: MMDFLUX_VIEW_RENDERER=kitty requires both kitten and rsvg-convert" >&2
                exit 1
            fi
            printf '%s\n' kitty
            ;;
        *)
            echo "scripts/view: unsupported MMDFLUX_VIEW_RENDERER=$VIEW_RENDERER (expected auto, chafa, or kitty)" >&2
            exit 1
            ;;
    esac
}

VIEW_RENDERER="$(resolve_view_renderer)"

if [[ "$VIEW_RENDERER" == "kitty" ]]; then
    KITTEN_WIDTH=""
    KITTEN_HEIGHT=""
    if KITTEN_SIZE="$(kitty_target_raster_size || true)"; then
        KITTEN_WIDTH="${KITTEN_SIZE%% *}"
        KITTEN_HEIGHT="${KITTEN_SIZE##* }"
    fi

    RSVG_ARGS=()
    if [[ -n "$KITTEN_WIDTH" && -n "$KITTEN_HEIGHT" ]]; then
        RSVG_ARGS=(--width "$KITTEN_WIDTH" --height "$KITTEN_HEIGHT" --keep-aspect-ratio)
    fi

    "${INPUT_CMD[@]}" \
        | cargo run -q -- "${MERGED_ARGS[@]}" ${EXTRA_ARGS[@]+"${EXTRA_ARGS[@]}"} \
        | rsvg-convert "${RSVG_ARGS[@]}" \
        | kitten icat --stdin=yes --fit=both --scale-up
else
    "${INPUT_CMD[@]}" \
        | cargo run -q -- "${MERGED_ARGS[@]}" ${EXTRA_ARGS[@]+"${EXTRA_ARGS[@]}"} \
        | chafa
fi