"""SRT 转 ASS 节点入口。

解析标准 SRT 后生成 ASS 文件，其中同一句字幕同时输出 LeftEye 与 RightEye
两个样式，分别落在屏幕左右两半，形成 VR 双眼叠加效果。
"""

from __future__ import annotations

import json
from pathlib import Path

from wov_sdk.models import InvokeRequest, InvokeResponse, NodeManifest
from wov_sdk.server import run_node


def _ass_header(resolution: str) -> str:
    """生成 ASS 文件头：脚本信息、左右眼样式和事件格式。"""
    width, height = resolution.lower().split("x", 1)
    # 左眼样式占左半边，右眼样式占右半边，各留 50px 内边距。
    left_margin = 50
    right_margin = int(width) - 50
    return f"""[Script Info]
Title: VR Dual-Eye Subtitle
ScriptType: v4.00+
Collisions: Normal
PlayResX: {width}
PlayResY: {height}
WrapStyle: 1
ScaledBorderAndShadow: yes

[V4+ Styles]
Format: Name,Fontname,Fontsize,PrimaryColour,SecondaryColour,OutlineColour,BackColour,Bold,Italic,Underline,StrikeOut,ScaleX,ScaleY,Spacing,Angle,BorderStyle,Outline,Shadow,Alignment,MarginL,MarginR,MarginV,Encoding
Style: LeftEye,Arial,50,&H00FFFFFF,&H000000FF,&H00000000,&H80000000,0,0,0,0,50,100,0,0,1,4,0,2,{left_margin},{int(width) // 2},{int(height) // 2 + 60},1
Style: RightEye,Arial,50,&H00FFFFFF,&H000000FF,&H00000000,&H80000000,0,0,0,0,50,100,0,0,1,4,0,2,{int(width) // 2},{right_margin},{int(height) // 2 + 60},1

[Events]
Format: Layer,Start,End,Style,Name,MarginL,MarginR,MarginV,Effect,Text
"""


def parse_srt(text: str) -> list[tuple[str, str, str]]:
    """把 SRT 文本解析为 (开始时间, 结束时间, 文本) 条目列表。"""
    entries: list[tuple[str, str, str]] = []
    lines = text.splitlines()
    index = 0
    while index < len(lines):
        # 跳过序号前的空行，兼容文件开头有换行的情况。
        if not lines[index].strip():
            index += 1
            continue
        # 跳过序号行，直接读取下一行时间轴。
        index += 1
        if index >= len(lines):
            break
        time_line = lines[index].strip()
        index += 1
        # 时间轴必须包含分隔符，否则按畸形输入跳过。
        if " --> " not in time_line:
            continue
        # SRT 使用逗号毫秒，ASS 使用点号，需要转换。
        start, end = [part.replace(",", ".") for part in time_line.split(" --> ")]
        # 连续读取非空行作为字幕文本，多行用 ASS 换行符 \N 连接。
        text_lines: list[str] = []
        while index < len(lines) and lines[index].strip():
            text_lines.append(lines[index])
            index += 1
        entries.append((start, end, r"\N".join(text_lines)))
        index += 1
    return entries


def write_ass(entries: list[tuple[str, str, str]], output_path: Path, resolution: str) -> None:
    """把解析后的条目写入 ASS 文件，每个条目输出左右眼两行 Dialogue。"""
    lines = [_ass_header(resolution)]
    for start, end, text in entries:
        # an2 对齐到屏幕中央偏下，保证双眼字幕视线自然。
        lines.append(f"Dialogue: 0,{start},{end},LeftEye,,0,0,0,,{{\\an2}}{text}")
        lines.append(f"Dialogue: 0,{start},{end},RightEye,,0,0,0,,{{\\an2}}{text}")
    output_path.write_text("\n".join(lines) + "\n", encoding="utf-8")


def invoke(request: InvokeRequest) -> InvokeResponse:
    """把 cn_srt_uri 指向的 SRT 转为 dual_eye.ass 产物。"""
    srt_uri = request.inputs.get("cn_srt_uri")
    if not srt_uri:
        return InvokeResponse(status="failed", error="cn_srt_uri is required")

    srt_path = Path(srt_uri)
    if not srt_path.is_file():
        return InvokeResponse(status="failed", error="srt file not found")

    entries = parse_srt(srt_path.read_text(encoding="utf-8"))
    output_dir = Path(request.output_dir)
    output_dir.mkdir(parents=True, exist_ok=True)
    output_path = output_dir / "dual_eye.ass"
    # 分辨率默认 3840x1920，覆盖常见 VR 视频尺寸。
    resolution = str(request.params.get("resolution", "3840x1920"))
    write_ass(entries, output_path, resolution)
    return InvokeResponse(status="completed", outputs={"ass_uri": str(output_path)})


def main() -> None:
    """加载节点清单并以本模块的 invoke 处理器启动服务。"""
    manifest_path = Path(__file__).resolve().parent.parent / "node.manifest.json"
    with open(manifest_path, "r", encoding="utf-8") as f:
        manifest = NodeManifest.from_dict(json.load(f))
    run_node(manifest, invoke)


if __name__ == "__main__":
    main()