#!/bin/sh

case "$0" in
    */*)
        MYDIR=${0%/*}
        ;;
    *)
        MYDIR=.
        ;;
esac

: ${MPV:=mpv}
: ${ILDETECT_MPV:=$MPV}
: ${ILDETECT_MPV:=$MPV}
: ${ILDETECT_MPVFLAGS:=--start=35% --length=35}
: ${ILDETECT_DRY_RUN:=}
: ${ILDETECT_QUIET:=}
: ${ILDETECT_RUN_INTERLACED_ONLY:=}
: ${ILDETECT_FORCE_RUN:=}
: ${MAKE:=make}

# exit status:
# 0 progressive
# 1 telecine
# 2 interlaced
# 8 unknown
# 16 detect fail
# 17+ mpv's status | 16

testfun()
{
    $ILDETECT_MPV "$@" \
        --vf=lavfi="[idet]" --msg-level ffmpeg=v \
        --o= --vo=null --no-audio --untimed \
        $ILDETECT_MPVFLAGS \
        | { if [ -n "$ILDETECT_QUIET" ]; then cat; else tee /dev/stderr; fi } \
        | grep "Parsed_idet_0: Multi frame detection: " | tail -n 1
}

judge()
{
    out=`testfun "$@"`

    tff=${out##* TFF:}; tff=${tff%% *}
    bff=${out##* BFF:}; bff=${bff%% *}
    progressive=${out##* Progressive:}; progressive=${progressive%% *}
    undetermined=${out##* Undetermined:}; undetermined=${undetermined%% *}

    case "$tff$bff$progressive$undetermined" in
        *[!0-9]*)
            echo >&2 "ERROR: Unrecognized idet output: $out"
            exit 16
            ;;
    esac

    interlaced=$((bff + tff))
    determined=$((interlaced + progressive))

    if [ $undetermined -gt $determined ] || [ $determined -lt 250 ]; then
        echo >&2 "ERROR: Less than 50% or 250 frames are determined."
        [ -n "$ILDETECT_FORCE_RUN" ] || exit 8
        echo >&2 "Assuming interlacing."
        if [ $tff -gt $((bff * 10)) ]; then
            verdict=interlaced-tff
        elif [ $bff -gt $((tff * 10)) ]; then
            verdict=interlaced-bff
        else
            verdict=interlaced
        fi
    elif [ $((interlaced * 20)) -gt $progressive ]; then
        # At least 5% of the frames are interlaced!
        if [ $tff -gt $((bff * 10)) ]; then
            verdict=interlaced-tff
        elif [ $bff -gt $((tff * 10)) ]; then
            verdict=interlaced-bff
        else
            echo >&2 "ERROR: Content is interlaced, but can't determine field order."
            [ -n "$ILDETECT_FORCE_RUN" ] || exit 8
            echo >&2 "Assuming interlacing with default field order."
            verdict=interlaced
        fi
    else
        # Likely progrssive.
        verdict=progressive
    fi

    echo "$verdict"
}

judge "$@"
case "$verdict" in
    progressive)
        [ -n "$ILDETECT_DRY_RUN" ] || \
            [ -n "$ILDETECT_RUN_INTERLACED_ONLY" ] || \
            $ILDETECT_MPV "$@"
        r=$?
        [ $r -eq 0 ] || exit $(($r | 16))
        exit 0
        ;;
    interlaced-tff)
        judge "$@" --vf-pre=pullup --field-dominance=top
        case "$verdict" in
            progressive)
                [ -n "$ILDETECT_DRY_RUN" ] || \
                    $ILDETECT_MPV "$@" --vf-pre=pullup --field-dominance=top
                r=$?
                [ $r -eq 0 ] || exit $(($r | 16))
                exit 1
                ;;
            *)
                [ -n "$ILDETECT_DRY_RUN" ] || \
                    $ILDETECT_MPV "$@" --vf-pre=yadif --field-dominance=top
                r=$?
                [ $r -eq 0 ] || exit $(($r | 16))
                exit 2
                ;;
        esac
        ;;
    interlaced-bff)
        judge "$@" --vf-pre=pullup --field-dominance=bottom
        case "$verdict" in
            progressive)
                [ -n "$ILDETECT_DRY_RUN" ] || \
                    $ILDETECT_MPV "$@" --vf-pre=pullup --field-dominance=bottom
                r=$?
                [ $r -eq 0 ] || exit $(($r | 16))
                exit 1
                ;;
            *)
                [ -n "$ILDETECT_DRY_RUN" ] || \
                    $ILDETECT_MPV "$@" --vf-pre=yadif --field-dominance=bottom
                r=$?
                [ $r -eq 0 ] || exit $(($r | 16))
                exit 2
                ;;
        esac
        ;;
    interlaced)
        judge "$@" --vf-pre=pullup
        case "$verdict" in
            progressive)
                [ -n "$ILDETECT_DRY_RUN" ] || \
                    $ILDETECT_MPV "$@" --vf-pre=pullup
                r=$?
                [ $r -eq 0 ] || exit $(($r | 16))
                exit 1
                ;;
            *)
                [ -n "$ILDETECT_DRY_RUN" ] || \
                    $ILDETECT_MPV "$@" --vf-pre=yadif
                r=$?
                [ $r -eq 0 ] || exit $(($r | 16))
                exit 2
                ;;
        esac
        ;;
    *)
        echo >&2 "ERROR: Internal error."
        exit 16
        ;;
esac