#!/bin/bash
# 图片预览脚本 - 优先 img2sixel (保持比例)，回退到 chafa
# 支持 Sixel 缓存以减少闪烁

img="$1"
width_chars="$2"
height_chars="$3"

# 缓存目录（请确保可写）
CACHE_DIR="$HOME/.cache/vifm/sixel_cache"
mkdir -p "$CACHE_DIR"

# 日志文件
LOG="$HOME/.config/vifm/scripts/img_preview.log"

# 强制使用符号模式（创建该文件可禁用所有 Sixel 尝试）
FORCE_SYMBOLS_FILE="$HOME/.config/vifm/force_preview_symbols"

mkdir -p "$(dirname "$LOG")"

echo "=== $(date) ===" >> "$LOG"
echo "File: $img" >> "$LOG"
echo "Chars: ${width_chars}x${height_chars}" >> "$LOG"

# 估算像素尺寸（用于 Sixel 工具）
font_width=32
font_height=64
pixel_width=$((width_chars * font_width))
pixel_height=$((height_chars * font_height))

# 限制最大像素尺寸（img2sixel 和 chafa 使用不同的限制）
MAX_WIDTH_IMG2SIXEL=940
MAX_HEIGHT_IMG2SIXEL=1600
MAX_WIDTH_CHAFA=150        # chafa 使用较小尺寸提升速度
MAX_HEIGHT_CHAFA=300

# 获取图片原始尺寸（需要 ImageMagick）
if command -v identify >/dev/null 2>&1; then
    orig_size=$(identify -format "%wx%h" "$img" 2>/dev/null)
    echo "Original size: $orig_size" >> "$LOG"
    orig_width=$(echo "$orig_size" | cut -d'x' -f1)
    orig_height=$(echo "$orig_size" | cut -d'x' -f2)
fi

# 辅助函数：计算保持比例的缩放尺寸
calculate_fit_size() {
    local w="$1" h="$2" max_w="$3" max_h="$4"
    local ratio_w=$(echo "scale=4; $max_w / $w" | bc)
    local ratio_h=$(echo "scale=4; $max_h / $h" | bc)
    local ratio=$(echo "scale=4; if ($ratio_w < $ratio_h) $ratio_w else $ratio_h" | bc)
    local new_w=$(echo "$w * $ratio" | bc | cut -d. -f1)
    local new_h=$(echo "$h * $ratio" | bc | cut -d. -f1)
    # 确保至少为1
    [ -z "$new_w" ] && new_w=1
    [ -z "$new_h" ] && new_h=1
    echo "${new_w}x${new_h}"
}

# 生成缓存键：基于图片路径、最终输出尺寸、工具名
get_cache_key() {
    local tool="$1"
    local out_w="$2"
    local out_h="$3"
    echo "$tool|$img|${out_w}x${out_h}" | md5sum | cut -d' ' -f1
}

# 尝试从缓存输出
try_cache() {
    local cache_file="$1"
    if [ -f "$cache_file" ] && [ -s "$cache_file" ]; then
        cat "$cache_file"
        echo "Used cache: $cache_file" >> "$LOG"
        return 0
    fi
    return 1
}

# ----- 优先尝试 img2sixel（保持比例）-----
if command -v img2sixel >/dev/null 2>&1; then
    echo "Trying img2sixel..." >> "$LOG"
    # 计算适应预览区域的缩放尺寸
    if [ -n "$orig_width" ] && [ -n "$orig_height" ]; then
        fit_size=$(calculate_fit_size "$orig_width" "$orig_height" "$pixel_width" "$pixel_height")
        fit_width=$(echo "$fit_size" | cut -d'x' -f1)
        fit_height=$(echo "$fit_size" | cut -d'x' -f2)
        echo "Fit size: ${fit_width}x${fit_height}" >> "$LOG"
    else
        # 无法获取原图尺寸，直接使用预览区域（会拉伸）
        fit_width="$pixel_width"
        fit_height="$pixel_height"
    fi

    # 限制最大尺寸
    [ "$fit_width" -gt "$MAX_WIDTH_IMG2SIXEL" ] && fit_width="$MAX_WIDTH_IMG2SIXEL"
    [ "$fit_height" -gt "$MAX_HEIGHT_IMG2SIXEL" ] && fit_height="$MAX_HEIGHT_IMG2SIXEL"

    # 生成缓存键并检查缓存
    cache_key=$(get_cache_key "img2sixel" "$fit_width" "$fit_height")
    cache_file="$CACHE_DIR/$cache_key.sixel"
    if try_cache "$cache_file"; then
        exit 0
    fi

    # 生成新的 Sixel
    tmpfile=$(mktemp)
    img2sixel --width "$fit_width" --height "$fit_height" "$img" > "$tmpfile" 2>&1
    exit_code=$?
    if [ $exit_code -eq 0 ] && [ -s "$tmpfile" ]; then
        if grep -q $'\x1bP' "$tmpfile" && grep -q $'\x1b\\\\' "$tmpfile"; then
            # 输出并缓存
            cat "$tmpfile"
            cp "$tmpfile" "$cache_file"
            echo "img2sixel succeeded (sixel, fit) and cached" >> "$LOG"
            rm -f "$tmpfile"
            exit 0
        else
            echo "img2sixel output missing sixel sequences" >> "$LOG"
        fi
    else
        echo "img2sixel failed (exit $exit_code, size $(stat -c%s "$tmpfile" 2>/dev/null))" >> "$LOG"
    fi
    rm -f "$tmpfile"
fi

# ----- 最后尝试 chafa sixel（保持比例，添加 --no-clear）-----
if command -v chafa >/dev/null 2>&1; then
    echo "Trying chafa sixel..." >> "$LOG"
    # 计算适应预览区域的缩放尺寸（使用字符尺寸估算）
    # 注意：chafa 的 --size 参数是像素，这里我们限制最大尺寸
    chafa_pixel_width=$((width_chars * 8))   # 假设字体宽8像素，可根据实际调整
    chafa_pixel_height=$((height_chars * 16)) # 假设字体高16像素

    # 限制最大尺寸（使用更保守的数值以提升性能）
    [ "$chafa_pixel_width" -gt "$MAX_WIDTH_CHAFA" ] && chafa_pixel_width="$MAX_WIDTH_CHAFA"
    [ "$chafa_pixel_height" -gt "$MAX_HEIGHT_CHAFA" ] && chafa_pixel_height="$MAX_HEIGHT_CHAFA"

    echo "Chafa pixel size: ${chafa_pixel_width}x${chafa_pixel_height}" >> "$LOG"

    # 生成缓存键并检查缓存
    cache_key=$(get_cache_key "chafa_sixel" "$chafa_pixel_width" "$chafa_pixel_height")
    cache_file="$CACHE_DIR/$cache_key.sixel"
    if try_cache "$cache_file"; then
        exit 0
    fi

    # 生成新的 Sixel（添加 --no-clear 禁止清屏）
    tmpfile=$(mktemp)
    chafa --format=sixel \
          --size="${chafa_pixel_width}x${chafa_pixel_height}" \
          "$img" > "$tmpfile" 2>/dev/null
    exit_code=$?
    if [ $exit_code -eq 0 ] && [ -s "$tmpfile" ]; then
        if grep -q $'\x1bP' "$tmpfile" && grep -q $'\x1b\\\\' "$tmpfile"; then
            cat "$tmpfile"
            cp "$tmpfile" "$cache_file"
            echo "chafa sixel succeeded and cached" >> "$LOG"
            rm -f "$tmpfile"
            exit 0
        else
            echo "chafa sixel missing start/end sequences" >> "$LOG"
        fi
    else
        echo "chafa sixel failed (exit $exit_code, size $(stat -c%s "$tmpfile" 2>/dev/null))" >> "$LOG"
    fi
    rm -f "$tmpfile"
fi

# ----- 最终回退：chafa 符号模式 -----
echo "Falling back to symbols mode" >> "$LOG"

echo "安装依赖："
echo "  sudo apt -y install foot,libsixel-bin"
exit 0