#!/usr/bin/env bash
# mtp (media tail parts) - play .part files while they are still downloading
#
# Usage:
#   mtp              - auto-detect newest .part or media file in current directory
#   mtp <file>       - play a specific file

# === COLORS ===
G='\033[1;32m'
Y='\033[1;33m'
C='\033[1;36m'
M='\033[1;35m'
R='\033[0m'

# === FILE SELECTION ===
if [ -n "$1" ]; then
    PART_FILE="$1"
    if [ ! -f "$PART_FILE" ]; then
        echo -e "${Y}❌ File not found: $PART_FILE${R}"
        exit 1
    fi
    echo -e "${C}📂 Using file from argument${R}"
else
    PART_FILE=$(ls -t *.part 2>/dev/null | head -1)
    if [ -z "$PART_FILE" ]; then
        PART_FILE=$(ls -t *.{mp4,mkv,webm,avi,mp3,opus,ogg,m4a,flac,wav} 2>/dev/null | head -1)
    fi
    if [ -z "$PART_FILE" ]; then
        echo -e "${Y}❌ No media files found in current directory${R}"
        exit 1
    fi
    echo -e "${C}📂 Auto-selected newest file${R}"
fi

# === WATCH LATER SETUP ===
WATCH_LATER_BASE="$HOME/.config/mpv/watch_later"
mkdir -p "$WATCH_LATER_BASE"

if [[ "$PART_FILE" == *.part ]]; then
    SESSION_DIR="$WATCH_LATER_BASE/downloading"
    echo -e "${Y}📥 Mode: Downloading (.part file)${R}"
    echo -e "${C}   Position saved temporarily (may shift as file grows)${R}"
else
    MTIME=$(stat -f%m "$PART_FILE" 2>/dev/null || stat -c%Y "$PART_FILE" 2>/dev/null)
    PART_FILE_SAFE=$(echo "$PART_FILE" | tr '/' '_' | tr ' ' '_')
    UNIQUE_SESSION="${PART_FILE_SAFE}_${MTIME}"
    SESSION_DIR="$WATCH_LATER_BASE/completed/$UNIQUE_SESSION"
    echo -e "${G}✅ Mode: Completed file${R}"
fi

mkdir -p "$SESSION_DIR"

# Permanent input config saved in session dir
INPUT_CONF="$SESSION_DIR/input.conf"
cat > "$INPUT_CONF" <<'EOF'
SPACE cycle pause
9 add volume -5
0 add volume +5
, seek -10
. seek +10
u quit 42
q quit
EOF

# === SHOW SAVED POSITION ===
_show_saved_pos() {
    local wl_file=$(find "$SESSION_DIR" -maxdepth 1 -type f ! -name "input.conf" 2>/dev/null | head -1)
    if [ -n "$wl_file" ]; then
        local saved_pos=$(grep "^start=" "$wl_file" 2>/dev/null | cut -d'=' -f2 | cut -d'.' -f1)
        if [ -n "$saved_pos" ]; then
            local saved_min=$((saved_pos / 60))
            local saved_sec=$((saved_pos % 60))
            echo -e "${G}💾 Resuming from:${R} ${saved_min}m ${saved_sec}s"
        fi
    fi
}

# === BUFFER WAIT ===
_wait_buffer() {
    local size=$(stat -f%z "$PART_FILE" 2>/dev/null || stat -c%s "$PART_FILE" 2>/dev/null)
    local size_mb=$(echo "scale=2; $size / 1048576" | bc)

    if [[ "$PART_FILE" == *.part ]]; then
        echo -e "${Y}⏳ Waiting for minimum buffer: 1 MB${R}"
        while [ "$size" -lt 1048576 ]; do
            sleep 1
            size=$(stat -f%z "$PART_FILE" 2>/dev/null || stat -c%s "$PART_FILE" 2>/dev/null)
            size_mb=$(echo "scale=2; $size / 1048576" | bc)
            echo -ne "\r${M}📊 Size:${R} ${size_mb} MB  "
        done
        echo -e "\n${G}✅ Minimum buffer reached: ${size_mb} MB${R}"
    fi
}

# === SHOW HEADER ===
_show_header() {
    local size=$(stat -f%z "$PART_FILE" 2>/dev/null || stat -c%s "$PART_FILE" 2>/dev/null)
    local size_mb=$(echo "scale=2; $size / 1048576" | bc)

    clear
    echo -e "${C}____________________________________________________________${R}"
    echo -e "${C}  MTP v1.1 | MEDIA TAIL PLAYER                             ${R}"
    echo -e "${C}____________________________________________________________${R}"
    echo -e "${Y}  9 / 0  : Volume down / up                             ${R}"
    echo -e "${Y}  , / .  : Seek -10 / +10 sec                       ${R}"
    echo -e "${Y}  SPACE  : Pause / Resume                               ${R}"
    echo -e "${Y}  u      : Refresh (keeps pos)                     ${R}"
    echo -e "${Y}  q      : Quit                                         ${R}"
    echo -e "${C}____________________________________________________________${R}"
    echo -e "${G}🎵 File:${R} $(basename "$PART_FILE")"
    echo -e "${M}📊 Size:${R} ${size_mb} MB"
    _show_saved_pos
    echo -e "${C}____________________________________________________________${R}"
}

# === MAIN PLAYBACK LOOP ===
_play_loop() {
    local size_session_start=$(stat -f%z "$PART_FILE" 2>/dev/null || stat -c%s "$PART_FILE" 2>/dev/null)

    while true; do
        _show_header

        mpv \
            --demuxer-lavf-o=fflags=+nobuffer+fastseek \
            --demuxer-readahead-secs=1 \
            --cache=yes \
            --cache-secs=10 \
            --demuxer-max-bytes=50M \
            --demuxer-max-back-bytes=20M \
            --stream-buffer-size=2M \
            --hr-seek=yes \
            --hr-seek-demuxer-offset=0 \
            --save-position-on-quit \
            --resume-playback \
            --watch-later-directory="$SESSION_DIR" \
            --input-conf="$INPUT_CONF" \
            --title="mtp: $(basename "$PART_FILE")" \
            "$PART_FILE"

        local exit_code=$?

        if [ $exit_code -eq 42 ]; then
            local size_new=$(stat -f%z "$PART_FILE" 2>/dev/null || stat -c%s "$PART_FILE" 2>/dev/null)
            local size_new_mb=$(echo "scale=2; $size_new / 1048576" | bc)
            local size_before=$(stat -f%z "$PART_FILE" 2>/dev/null || stat -c%s "$PART_FILE" 2>/dev/null)
            local gained=$(echo "scale=2; ($size_new - $size_before) / 1048576" | bc)
            echo -e "\n${G}🔄 Refreshed — size: ${size_new_mb} MB${R}"
            echo -e "${C}   Resuming from saved position...${R}"
            sleep 1
            continue
        else
            echo ""
            if [ $exit_code -eq 0 ]; then
                echo -e "${G}✅ Playback finished${R}"
            else
                echo -e "${Y}⚠️  Interrupted (code: $exit_code)${R}"
            fi
            break
        fi
    done

    # Final summary
    local size_end=$(stat -f%z "$PART_FILE" 2>/dev/null || stat -c%s "$PART_FILE" 2>/dev/null)
    local size_end_mb=$(echo "scale=2; $size_end / 1048576" | bc)
    local total_diff_mb=$(echo "scale=2; ($size_end - $size_session_start) / 1048576" | bc)

    echo -e "${C}____________________________________________________________${R}"
    echo -e "${M}📊 Size at end:${R} ${size_end_mb} MB"
    if [ "$total_diff_mb" != "0.00" ]; then
        echo -e "${G}📈 Downloaded during session:${R} +${total_diff_mb} MB"
    fi
    echo -e "${C}____________________________________________________________${R}"
}

# === RUN ===
_wait_buffer
_play_loop