#!/bin/bash
# File operation functions for torrent-mover

# init_checksum_db: Initializes the checksum database.
init_checksum_db() {
    mkdir -p "$(dirname "${CHECKSUM_DB}")"
    touch "${CHECKSUM_DB}" || { log_error "Could not create ${CHECKSUM_DB}"; exit 1; }
    chmod 600 "${CHECKSUM_DB}"
}

# record_checksums: Generates checksums for files in given directories.
record_checksums() {
    log_info "Generating checksums with ${PARALLEL_THREADS:-$(nproc)} threads"
    find "$@" -type f ! \( -iname "*.nfo" -o -iname "*.sfv" \) -print0 | \
        parallel -0 -j ${PARALLEL_THREADS:-$(nproc)} md5sum | sort > "${CHECKSUM_DB}.tmp"
    mv "${CHECKSUM_DB}.tmp" "${CHECKSUM_DB}"
}

# file_metadata: Returns an md5 hash for file metadata.
file_metadata() {
    find "$1" -type f ! \( -iname "*.nfo" -o -iname "*.sfv" \) -exec md5sum {} \; | sort | awk '{print $1}'
}

# files_need_processing: Checks if the source files need processing.
files_need_processing() {
    local src="$1"
    shift
    local targets=("$@")
    
    if [[ ! -d "${src}" ]]; then
        log_warn "Source directory missing: ${src}"
        return 1
    fi

    log_info "=== FILE VERIFICATION DEBUG START ==="
    log_info "Source directory: ${src}"
    log_info "Verification targets: ${targets[*]}"

    local empty_target_found=0
    for target in "${targets[@]}"; do
        if [[ ! -d "${target}" ]]; then
            log_info "Target missing: ${target}"
            empty_target_found=1
            continue
        fi

        local file_count
        file_count=$(find "${target}" -mindepth 1 -maxdepth 1 -print | wc -l)
        log_debug "File count for target ${target}: ${file_count}"
        if [[ "${file_count}" -eq 0 ]]; then
            log_info "Empty target directory: ${target}"
            empty_target_found=1
        else
            log_info "Target contains ${file_count} items: ${target}"
            log_info "First 5 items:"
            find "${target}" -mindepth 1 -maxdepth 1 | head -n 5 | while read -r item; do
                log_info "    - ${item##*/}"
            done
        fi
    done

    if [[ "${empty_target_found}" -eq 1 ]]; then
        log_info "Empty target detected - processing needed"
        log_info "=== FILE VERIFICATION DEBUG END ==="
        return 0
    fi

    log_info "Generating source checksums..."
    local src_checksums
    src_checksums=$(find "${src}" -type f ! \( -iname "*.nfo" -o -iname "*.sfv" \) -exec md5sum {} \; | sort)
    log_info "First 5 source checksums:"
    echo "${src_checksums}" | head -n 5 | while read -r line; do
        log_info "    ${line}"
    done

    local match_found=0
    for target in "${targets[@]}"; do
        log_info "Checking against target: ${target}"
        log_info "Generating target checksums..."
        local target_checksums
        target_checksums=$(find "${target}" -type f ! \( -iname "*.nfo" -o -iname "*.sfv" \) -exec md5sum {} \; | sort)
        log_info "First 5 target checksums:"
        echo "${target_checksums}" | head -n 5 | while read -r line; do
            log_info "    ${line}"
        done

        if diff <(echo "${src_checksums}") <(echo "${target_checksums}") >/dev/null; then
            log_info "Exact checksum match found in: ${target}"
            match_found=1
            break
        else
            log_info "No match in: ${target}"
        fi
    done

    log_info "=== FILE VERIFICATION DEBUG END ==="
    [[ "${match_found}" -eq 1 ]] && return 1 || return 0
}

# warm_cache: Pre-calculates checksums for storage directories.
warm_cache() {
    log_info "Starting cache warmup for Movies..."
    local targets=("${DIR_MOVIES_DST}" "${STORAGE_DIRS_ARRAY[@]}")
    record_checksums "${targets[@]}"
    log_info "Cache warmup completed. Checksums stored in ${CHECKSUM_DB}"
}

# is_processed: Checks if the torrent (by hash) has already been processed.
is_processed() {
    grep -q "^${1}$" "${PROCESSED_LOG}" 2>/dev/null
}

# mark_processed: Records a processed torrent.
mark_processed() {
    echo "${1}" >> "${PROCESSED_LOG}"
}

# move_files: Moves files using parallel processing if enabled.
move_files() {
    if (( PARALLEL_PROCESSING )); then
        retry_command "parallel -j ${PARALLEL_THREADS:-$(nproc)} mv {} \"${1}\" ::: \"${2}\"/*" 3 15
    else
        retry_command "mv \"${2}\"/* \"${1}\"" 3 15
    fi
}

# copy_files: Copies files using parallel processing if enabled.
copy_files() {
    if (( PARALLEL_PROCESSING )); then
        retry_command "parallel -j ${PARALLEL_THREADS:-$(nproc)} cp -r {} \"${1}\" ::: \"${2}\"/*" 3 15
    else
        retry_command "cp -r \"${2}\"/* \"${1}\"" 3 15
    fi
}

# process_copy: Validates directories, then copies/moves files from source to destination.
# Optionally verifies integrity after transfer if CHECK_TRANSFER_INTEGRITY is "true".
process_copy() {
    local id="$1" hash="$2" src="$3" dst="$4"
    if [[ ! -d "${src}" ]]; then
        log_error "Source directory missing: ${src}"
        return 1
    fi
    if [[ ! -d "${dst}" ]]; then
        log_info "Creating destination directory: ${dst}"
        mkdir -p "${dst}" || { log_error "Failed to create directory: ${dst}"; return 1; }
        chmod 775 "${dst}"
        chown ${TORRENT_USER:-debian-transmission}:${TORRENT_GROUP:-debian-transmission} "${dst}"
    fi
    if [[ ! -w "${dst}" ]]; then
        log_error "No write permissions for: ${dst}"
        return 1
    fi
    if (( DRY_RUN )); then
        log_info "[DRY RUN] Would process torrent ${id}:"
        log_info "  - Copy files from ${src} to ${dst}"
        log_info "  - File count: $(find "${src}" -maxdepth 1 -type f | wc -l)"
        return
    fi
    handle_archives "${src}" "${dst}"
    case "${COPY_MODE}" in
        move)
            log_info "Moving files from ${src} to ${dst}"
            move_files "${dst}" "${src}"
            ;;
        copy)
            log_info "Copying files from ${src} to ${dst}"
            copy_files "${dst}" "${src}"
            ;;
    esac
    if [ $? -eq 0 ]; then
        if [[ "${CHECK_TRANSFER_INTEGRITY}" == "true" ]]; then
            log_info "Verifying integrity of transferred files..."
            local src_checksum target_checksum
            src_checksum=$(find "${src}" -type f ! \( -iname "*.nfo" -o -iname "*.sfv" \) -exec md5sum {} \; | sort)
            target_checksum=$(find "${dst}" -type f ! \( -iname "*.nfo" -o -iname "*.sfv" \) -exec md5sum {} \; | sort)
            if diff <(echo "${src_checksum}") <(echo "${target_checksum}") >/dev/null; then
                log_info "Integrity check passed."
            else
                log_error "Integrity check FAILED for ${src}"
                return 1
            fi
        fi
        log_info "Transfer completed successfully"
        mark_processed "${hash}"
    else
        log_error "Transfer failed for ${src}"
        return 1
    fi
    return 0
}