from typing import List
import json
from .base import EffectProcessor

class ZoomEffect(EffectProcessor):
    """缩放效果处理器"""
    
    def validate_params(self) -> bool:
        """验证参数：start_time,zoom_factor,duration"""
        params = self.parse_params()
        if len(params) < 3:
            return False
            
        try:
            start_time = float(params[0])
            zoom_factor = float(params[1])
            duration = float(params[2])
            
            return (start_time >= 0 and
                   zoom_factor > 0 and
                   duration >= 0)
        except (ValueError, IndexError):
            return False
            
    def generate_filter_args(self, video_input: str, effect_index: int) -> tuple[List[str], str]:
        """生成缩放效果的滤镜参数"""
        if not self.validate_params():
            return [], video_input
            
        params = self.parse_params()
        start_time = float(params[0])
        zoom_factor = float(params[1]) 
        duration = float(params[2])
        
        if zoom_factor == 1:
            return [], video_input  # 不需要缩放
            
        output_stream = f"[v_eff{effect_index}]"
        
        # 获取缩放中心点
        center_x, center_y = self._get_zoom_center()
        
        filter_args = []
        
        if duration == 0:
            # 静态缩放（整个视频时长）
            x_expr = f"({center_x})-(ow*zoom)/2"
            y_expr = f"({center_y})-(oh*zoom)/2"
            filter_args.append(
                f"{video_input}trim=start={start_time},zoompan=z={zoom_factor}:x={x_expr}:y={y_expr}:d=1{output_stream}"
            )
        else:
            # 动态缩放（指定时间段内）
            zoom_expr = f"if(between(t\\,{start_time}\\,{start_time + duration})\\,{zoom_factor}\\,1)"
            x_expr = f"({center_x})-(ow*zoom)/2"
            y_expr = f"({center_y})-(oh*zoom)/2"
            filter_args.append(
                f"{video_input}zoompan=z={zoom_expr}:x={x_expr}:y={y_expr}:d=1{output_stream}"
            )
            
        return filter_args, output_stream
        
    def _get_zoom_center(self) -> tuple[str, str]:
        """获取缩放中心点坐标表达式"""
        # 默认中心点
        center_x = "iw/2"
        center_y = "ih/2"
        
        pos_json = self.get_pos_json()
        if pos_json:
            _f_x = pos_json.get('ltX', 0)
            _f_x2 = pos_json.get('rbX', 0)
            _f_y = pos_json.get('ltY', 0)
            _f_y2 = pos_json.get('rbY', 0)
            _v_w = pos_json.get('imgWidth', 1)
            _v_h = pos_json.get('imgHeight', 1)
            
            if _v_w > 0 and _v_h > 0:
                # 计算坐标系统中的中心点
                center_x_ratio = (_f_x + _f_x2) / (2 * _v_w)
                center_y_ratio = (_f_y + _f_y2) / (2 * _v_h)
                # 转换为视频坐标系统
                center_x = f"iw*{center_x_ratio:.6f}"
                center_y = f"ih*{center_y_ratio:.6f}"
                
        return center_x, center_y
        
    def get_effect_name(self) -> str:
        return "zoom"