fzf

#!/usr/bin/env sh
# vim: ft=sh ts=4 sw=4 sts=4 et :

# Hijack fzf command for extra functionality, including adaptive height,
# flexible preview window layout, and image preview with ueberzugpp

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

# Get terminal size
lines=$(has tput && tput lines || echo "${LINES:-24}")
cols=$(has tput && tput cols || echo "${COLUMNS:-80}")

# Get cursor position or return 1;1 if not available
# Source:
# https://stackoverflow.com/questions/2575037/how-to-get-the-cursor-position-in-bash
cursorpos() {
    # R/w to /dev/tty blocks in nvim's `jobstart()`
    if [ -n "$NVIM" ]; then
        echo '1;1'
        return
    fi

    # Try opening /dev/tty, return fake cursor position if it fails
    if ! { exec 3<>/dev/tty; } 2>/dev/null; then
        echo '1;1'
        return
    fi

    # Test reading from tty with timeout, return fake cursor position if timeout
    read -t 0.1 -n 0 <>/dev/tty || {
        exec 3>&-
        echo '1;1'
        return
    }
    exec 3>&-

    # Now we can safely access /dev/tty
    exec </dev/tty
    oldstty=$(stty -g)
    stty raw -echo min 0
    printf '\033[6n' >/dev/tty

    # Read cursor position response
    pos=$(dd count=1 bs=32 2>/dev/null)
    stty "$oldstty"

    # Parse response of format "ESC[row;colR"
    case "$pos" in
    *'['*';'*R*)
        row=${pos#*[}
        row=${row%;*}
        col=${pos#*;}
        col=${col%R}
        echo "$((row - 1));$((col - 1))"
        ;;
    *)
        echo '1;1'
        ;;
    esac
}

# Normalize percentage to number
normalize_fzf_geometry() {
    # $1: number or percentage
    # $2: total
    case "$1" in
    *%) echo "$((${1%\%} * $2 / 100))" ;;
    *) echo "$1" ;;
    esac
}

# Get fzf option value
get_fzf_long_opt_no_space() {
    # $1: long option name
    # $2: default value of the option if not set
    if ! has grep; then
        echo "$2"
        return 1
    fi

    val=$(printf '%s' "$FZF_DEFAULT_OPTS" | grep -o -- "--$1=[^ ]*" | tail -n1)
    val=${val#--$1=}
    val=${val#[\"\']}
    val=${val%[\"\']}

    [ -z "$val" ] && echo "$2" || echo "$val"
}

# Get fzf margin or padding from $FZF_DEFAULT_OPTS environment variable fzf
# exports $FZF_PREVIEW_{COLUMNS,LINES} so that previewer can adjust its size
# accordingly but information about padding and margin is not provided, so we
# have to calculate it according to $FZF_DEFAULT_OPTS, this is not ideal since
# it won't work if user overrides the preview window settings in $@
get_fzf_geometry_normalized() {
    # $1: 'margin' or 'padding'
    # $2: 'top', 'bottom', 'left', or 'right'
    geometry=$(get_fzf_long_opt_no_space "$1" 0)
    [ $? -ne 0 ] && echo "$geometry" && return 1

    case "$2" in
    top | bottom) total=$lines ;;
    *) total=$cols ;;
    esac

    case "$geometry" in
    [0-9]*% | [0-9]*)
        normalize_fzf_geometry "$geometry" "$total"
        ;;
    [0-9]*%,[0-9]*% | [0-9]*,[0-9]*)
        case "$2" in
        top | bottom) val=${geometry%%,*} ;;
        *) val=${geometry##*,} ;;
        esac
        normalize_fzf_geometry "$val" "$total"
        ;;
    *)
        echo 0
        ;;
    esac
}

main() {
    # Create temporary directory
    tmp_dir=$(mktemp -d -t "$(basename "$0").XXXXXXXX")
    [ ! -d "$tmp_dir" ] && echo 'Failed to create temp dir' >&2 && return 1

    trap 'rm -rf "$tmp_dir"' HUP INT QUIT ABRT EXIT

    # Link files to avoid recursion
    script_dir=$(dirname "$0")
    for file in "$script_dir"/*; do
        [ "$file" = "$0" ] && continue
        ln -s "$file" "$tmp_dir"
    done

    # Update PATH
    PATH=$(printf '%s' "$PATH" | tr ':' '\n' | sed "s|^$script_dir\$|$tmp_dir|" | tr '\n' ':' | sed 's/:$//')

    if ! has fzf; then
        echo 'fzf not found' >&2
        return 1
    fi

    # Calculate adaptive height
    cursor=$(cursorpos)
    cursor_row=${cursor%;*}
    fzf_height=$((lines - cursor_row - 1))
    min_height=$(get_fzf_long_opt_no_space min-height 10)

    [ "$fzf_height" -lt "$min_height" ] && fzf_height=$min_height
    [ "$fzf_height" -gt "$lines" ] && fzf_height=$lines

    opts="--height=$fzf_height"

    # Calculate preview window layout
    margin_top=$(get_fzf_geometry_normalized margin top)
    margin_right=$(get_fzf_geometry_normalized margin right)
    margin_bottom=$(get_fzf_geometry_normalized margin bottom)
    margin_left=$(get_fzf_geometry_normalized margin left)
    padding_top=$(get_fzf_geometry_normalized padding top)
    padding_right=$(get_fzf_geometry_normalized padding right)
    padding_bottom=$(get_fzf_geometry_normalized padding bottom)
    padding_left=$(get_fzf_geometry_normalized padding left)

    inner_height=$((fzf_height - margin_top - margin_bottom - padding_top - padding_bottom))
    inner_width=$((cols - margin_left - margin_right - padding_left - padding_right))

    [ "$inner_height" -lt 1 ] && inner_height=1
    [ "$inner_width" -lt 1 ] && inner_width=1

    if [ "$inner_height" -gt 16 ] || [ "$inner_width" -gt 48 ]; then
        if [ "$inner_width" -gt $((inner_height * 3)) ] && [ "$inner_width" -ge 80 ]; then
            preview_window_orientation='right'
        else
            preview_window_orientation='down'
        fi
        opts="$opts --preview-window=$preview_window_orientation"
    else
        opts="$opts --no-preview"
        preview_disabled=true
    fi

    # Setup ueberzugpp if available
    if has ueberzugpp && [ "$FZF_PREVIEW_DISABLE_UB" != 'true' ] && [ "$preview_disabled" != 'true' ]; then
        ub_pid_file="/tmp/.$(uuidgen)"
        ueberzugpp layer --silent --no-stdin --use-escape-codes --pid-file "$ub_pid_file" >/dev/null 2>&1

        # Export variables for previewer
        UB_SOCK="/tmp/ueberzugpp-$(cat "$ub_pid_file").socket"
        export UB_SOCK
        export FZF_PREVIEW_ORIENTATION="$preview_window_orientation"
        export FZF_HEIGHT="$fzf_height"
        export FZF_MARGIN_TOP="$margin_top"
        export FZF_MARGIN_RIGHT="$margin_right"
        export FZF_MARGIN_BOTTOM="$margin_bottom"
        export FZF_MARGIN_LEFT="$margin_left"
        export FZF_PADDING_TOP="$padding_top"
        export FZF_PADDING_RIGHT="$padding_right"
        export FZF_PADDING_BOTTOM="$padding_bottom"
        export FZF_PADDING_LEFT="$padding_left"
        export FZF_TERM_LINES="$lines"
        export FZF_TERM_COLUMNS="$cols"
    fi

    # Run fzf with our options
    FZF_DEFAULT_OPTS="$FZF_DEFAULT_OPTS $opts" fzf "$@"

    # Cleanup ueberzugpp
    [ -n "$UB_SOCK" ] && ueberzugpp cmd -s "$UB_SOCK" -a exit &
    [ -e "$ub_pid_file" ] && rm -f "$ub_pid_file" &
}

main "$@"