#!/bin/bash

debug() { echo "🛠️ DEBUG: $*" >&2; }

# Convert .avi and .mkv files to .mp4
# Supports --dry-run to simulate actions
# --source is required; --archive is optional

set -euo pipefail

# --- Defaults ---
DRY_RUN=false
DEBUG=false
SRC_DIR=""
ARCHIVE_DIR=""
LOG_FILE="log.convert"
QUALITY="23"

SRC_TYPES=()

# --- Help Message ---
show_help() {
  echo "Usage: $0 --source <src_dir> [--archive <archive_dir>] [--quality ] [--dry-run] [--debug]"
  echo
  echo "  --source      Directory to scan for .avi and .mkv files"
  echo "  --archive     Directory to move originals after conversion (optional)"
  echo "                If omitted, originals will be deleted"
  echo "  --quality     Quality of the video 18-28 (18 is high quality, 23 is default, 28 is low)"
  echo "  --dry-run     Show actions without performing them"
  echo "  --debug       Output debug statements"
  echo
  exit 1
}

# --- Parse Arguments ---
while [[ $# -gt 0 ]]; do
  case "$1" in
    --source)
      SRC_DIR="$(realpath "$2")"
      shift 2
      ;;
    --archive)
      ARCHIVE_DIR="$(realpath "$2")"
      shift 2
      ;;
    --dry-run)
      DRY_RUN=true
      shift
      ;;
    --debug)
      DEBUG=true
      shift
      ;;
    --src-type)
      SRC_TYPES+=("${2,,}") # normalize to lowercase
      shift -2
      ;;
    --help|-h)
      show_help
      ;;
    --quality)
      QUALITY="$2"
      if ! [[ "$QUALITY" =~ ^[0-9]+$ ]] || ((QUALITY < 18 || QUALITY > 28)); then
        echo "❌ Error: --quality must be an integer between 18 and 28." >&2
        exit 1
      fi
      shift 2
      ;;
    *)
      echo "Unknown option: $1"
      show_help
      ;;
  esac
done

if [[ "${#SRC_TYPES[@]}" -eq 0 ]]; then
  SRC_TYPES=("avi" "mkv")   # default id none specified
fi

# --- Validate Source Directory ---
if [[ -z "$SRC_DIR" ]]; then
  echo "❌ Error: --source is required." >&2
  show_help
fi

if [[ ! -d "$SRC_DIR" ]]; then
  echo "❌ Error: Source directory does not exist: $SRC_DIR" >&2
  exit 1
fi

echo "🔍 Scanning: $SRC_DIR"
$DRY_RUN && echo "🧪 Dry-run mode enabled"

# --- Gather file list once ---
mapfile -d '' FILE_LIST < <(find "$SRC_DIR" \( -iname '*.avi' -o -iname '*.mkv' \) -print0)

# --- Preview list if in debug mode ---
if [[ "${DEBUG:-false}" == "true" ]]; then
  echo "🗂️ DEBUG: File list to process:"
  for file in "${FILE_LIST[@]}"; do
    echo "  - $file"
  done
fi


# --- Find and Process Files ---
# Using process substitution instead of a pipe, so the while loop runs in the current shell
for src_file in "${FILE_LIST[@]}"; do
  # abs_src_file="$(realpath "$src_file")"
  # rel_path="${abs_src_file#$SRC_DIR/}"

  # Use absolute path If the source file path is not absolute
  # (doesn't start with '/'), prepend the source directory to
  # make it an absolute path.
  [[ "$src_file" != /* ]] && src_file="$SRC_DIR/$src_file"

  rel_path="${src_file#$SRC_DIR/}"

  base_name="${rel_path%.*}"
  dst_file="$SRC_DIR/$base_name.mp4"

  echo "▶️ Converting: $rel_path"

  if $DRY_RUN; then
    echo "  [dry-run] Would convert to: $dst_file"
    [[ -n "$ARCHIVE_DIR" ]] && echo "  [dry-run] Would move original to: $ARCHIVE_DIR/$rel_path" || echo "  [dry-run] Would delete original"
    continue
  fi

  # Create output directory if needed
  mkdir -p "$(dirname "$dst_file")"

  if [[ "${DEBUG:-false}" == "true" ]]; then
    debug "dirname dst_file: $(dirname "$dst_file")"
    debug "src_file: $src_file"
    # debug "abs_src_file: $abs_src_file"
    debug "rel_path: $rel_path"
    debug "base_name: $base_name"
    debug "dst_file: $dst_file"
    debug ""
    debug "command:"
    debug "ffmpeg -i \"$src_file\" -c:v libx264 -preset slow -crf $QUALITY -c:a aac -b:a 128k -movflags +faststart \"$dst_file\" -y >> $LOG_FILE 2>&1"
  fi

  # Convert video with ffmpeg and log output
  ffmpeg \
    -i "$src_file" \
    -c:v libx264 \
    -preset slow \
    -crf "$QUALITY" \
    -c:a aac \
    -b:a 128k \
    -movflags +faststart \
    "$dst_file" \
    -y >> "$LOG_FILE" 2>&1

  # Archive or delete original
  if [[ -n "$ARCHIVE_DIR" ]]; then
    archive_file="$ARCHIVE_DIR/$rel_path"
    mkdir -p "$(dirname "$archive_file")"
    mv "$src_file" "$archive_file"
  else
    rm "$src_file"
  fi
done

echo "✅ Done."