docparser-pdf 0.1.0

//! docparser PDF 后端：`pdfium-worker`（PDFium 常驻 worker 线程 + 通道请求/响应）。
//!
//! 架构（发布形态 06 + PDF_TODO"native 调用进 worker 线程"）：
//!   * 一条 worker 线程独占持有 `Pdfium`（含裸指针，非 Sync），进程内只此一处 native
//!     状态；能力对象经 `mpsc` 通道发路径、收 `RawDoc`——避开了在 trait 对象里持有
//!     Pdfium 的 Send/Sync 困境，也与 Python 参考实现的 PDF-0.1 语义对齐。
//!   * 逐文本对象抽取 text + bbox（pt，左上原点），支持 CJK CID 字体（PDFium 内建
//!     CMap，不依赖 ToUnicode）——解决 pdf-extract v1 的中文盲区。
//!   * 错误分类：ENCRYPTED / CORRUPT。
//!   * 兜底后端 `pdfium-text-v1`（pdf-extract，纯 Rust）：worker 缺失或解析失败时
//!     按 BackendPolicy 链回退（encrypted/unsupported 为终止码，不回退）。

use std::sync::mpsc;
use std::sync::{Arc, Mutex, OnceLock};

use pdfium_render::prelude::*;

use docparser_core::error::{DocError, ErrorCode, Result};
use docparser_core::model::{BlockKind, Document, Page, Rect};
use docparser_core::plugin::{
    BackendKind, FormatPlugin, ParseCapability, RawDoc, RawImage, RawPage, RawTextItem,
};
use docparser_core::registry::Registry;

type Resp = Result<RawDoc>;

/// 运行时 PDFium 库发现：`DOCPARSER_PDFIUM_LIB` → 开发环境 pypdfium2 自带 → 无。
pub fn find_library() -> Option<std::path::PathBuf> {
    if let Ok(p) = std::env::var("DOCPARSER_PDFIUM_LIB") {
        let p = std::path::PathBuf::from(p);
        if p.exists() {
            return Some(p);
        }
    }
    let home = std::env::var("HOME").unwrap_or_default();
    #[cfg(target_os = "macos")]
    let name = "libpdfium.dylib";
    #[cfg(target_os = "linux")]
    let name = "libpdfium.so";
    #[cfg(target_os = "windows")]
    let name = "pdfium.dll";
    // P7 自包含发布：<exe>/../lib/<libpdfium> 优先（bundle 无 env 也可跑）
    if let Ok(exe) = std::env::current_exe() {
        if let Some(dir) = exe.parent() {
            let p = dir.join("..").join("lib").join(name);
            if p.exists() {
                return Some(p);
            }
        }
    }
    for base in [
        // liteparse 附带库（实测可与 pdfium-render 绑定成功）
        format!("{home}/miniconda3/lib/python3.13/site-packages/liteparse"),
        // pypdfium2 v5 原生库独立分发包
        format!("{home}/miniconda3/lib/python3.13/site-packages/pypdfium2_raw"),
        format!("{home}/miniconda3/envs/kb/lib/python3.13/site-packages/pypdfium2_raw"),
    ] {
        let p = std::path::Path::new(&base).join(name);
        if p.exists() {
            return Some(p);
        }
    }
    None
}

fn classify(e: &PdfiumError) -> DocError {
    let msg = format!("{e}").to_lowercase();
    if msg.contains("password") || msg.contains("encrypt") || msg.contains("permission") {
        DocError::encrypted(format!("PDF 加密或权限受限: {e}"))
    } else {
        DocError::corrupt(format!("PDF 打开/解析失败: {e}"))
    }
}

static RENDER_SEQ: std::sync::atomic::AtomicUsize = std::sync::atomic::AtomicUsize::new(0);

pub fn find_ocr_binary() -> Option<std::path::PathBuf> {
    if let Ok(p) = std::env::var("DOCPARSER_OCR_BIN") {
        let p = std::path::PathBuf::from(p);
        if p.exists() {
            return Some(p);
        }
    }
    // P7 自包含发布：与 CLI 同 bin 目录的 docparser-ocr
    if let Ok(exe) = std::env::current_exe() {
        if let Some(dir) = exe.parent() {
            let p = dir.join("docparser-ocr");
            if p.exists() {
                return Some(p);
            }
        }
    }
    // CARGO_MANIFEST_DIR 相对（rust/pdf → rust/target，workspace 共享 target）
    let cands = [
        std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("../target/release/docparser-ocr"),
        std::path::PathBuf::from("rust/target/release/docparser-ocr"),
    ];
    cands.into_iter().find(|c| c.exists())
}

pub fn find_ocr_models() -> Option<std::path::PathBuf> {
    if let Ok(p) = std::env::var("DOCPARSER_OCR_MODELS") {
        let p = std::path::PathBuf::from(p);
        if p.is_dir() {
            return Some(p);
        }
    }
    // P7 自包含发布：<exe>/../models/ocr/ppocrv5
    if let Ok(exe) = std::env::current_exe() {
        if let Some(dir) = exe.parent() {
            let p = dir.join("..").join("models/ocr/ppocrv5");
            if p.is_dir() {
                return Some(p);
            }
        }
    }
    let cands = [
        std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("../../models/ocr/ppocrv5"),
        std::path::PathBuf::from("models/ocr/ppocrv5"),
    ];
    cands.into_iter().find(|c| c.is_dir())
}

/// 乱码字符判定（对齐 Python `_is_garbled_char`）：替换符 U+FFFD 与私用区 U+E000–U+F8FF。
fn is_garbled_char(ch: char) -> bool {
    let cp = ch as u32;
    ch == '\u{fffd}' || (0xE000..=0xF8FF).contains(&cp)
}

/// 页级复杂度判定（对齐 Python `compute_complexity`）：
/// needs_ocr = chars<10（no-text / sparse-text）或 garbled_ratio>0.3。
fn page_needs_ocr(texts: &[String]) -> bool {
    let chars: usize = texts.iter().map(|t| t.trim().chars().count()).sum();
    if chars < 10 {
        return true;
    }
    let garbled: usize = texts
        .iter()
        .flat_map(|t| t.chars())
        .filter(|c| is_garbled_char(*c))
        .count();
    garbled as f32 / chars as f32 > 0.3
}

/// 常见位图扩展名嗅探（png/jpg/bmp/gif/webp）；否则 None（走位图回退）。
fn sniff_ext(data: &[u8]) -> Option<&'static str> {
    if data.len() >= 8 && data.starts_with(&[0x89, b'P', b'N', b'G', 0x0D, 0x0A, 0x1A, 0x0A]) {
        return Some("png");
    }
    if data.len() >= 3 && data[0] == 0xFF && data[1] == 0xD8 && data[2] == 0xFF {
        return Some("jpg");
    }
    if data.len() >= 2 && data.starts_with(b"BM") {
        return Some("bmp");
    }
    if data.len() >= 4 && data.starts_with(b"GIF8") {
        return Some("gif");
    }
    if data.len() >= 12 && data.starts_with(b"RIFF") && &data[8..12] == b"WEBP" {
        return Some("webp");
    }
    None
}

/// 嵌入图 OCR 过滤（对齐 Python `_ocrable_image`）：ext 白名单 + min(px)≥50。
fn ocrable_image(im: &RawImage) -> bool {
    if im.data.is_empty() {
        return false;
    }
    if !matches!(
        im.ext.as_str(),
        "png" | "jpg" | "jpeg" | "bmp" | "gif" | "webp"
    ) {
        return false;
    }
    if let Some((w, h)) = im.px {
        return w.min(h) >= 50;
    }
    false
}

/// 收集页内嵌入图片（含 Form XObject 嵌套，深度≤2，对齐 Python `_page_images`）。
/// bbox 换算页面 pt（左上原点）。
///
/// lazy 语义：默认（`ocr_images=false`）只取元数据（bbox/px）不解码字节，避免文本优先
/// 路径为图付解码成本（liteparse 关 OCR 语义）；`extract_data=true` 时才取原始流/回退
/// 处理位图转 PNG（供嵌入图 OCR 使用）。
fn collect_page_images(
    doc: &PdfDocument,
    page: &PdfPage,
    h: f32,
    extract_data: bool,
) -> Vec<RawImage> {
    let mut out: Vec<RawImage> = Vec::new();
    descend(doc, page.objects().iter(), h, 0, extract_data, &mut out);
    out
}

fn descend<'a>(
    doc: &'a PdfDocument,
    objs: impl Iterator<Item = PdfPageObject<'a>>,
    h: f32,
    depth: usize,
    extract_data: bool,
    out: &mut Vec<RawImage>,
) {
    if depth > 2 {
        return;
    }
    for obj in objs {
        if let Some(img) = obj.as_image_object() {
            let bbox = obj.bounds().ok().map(|q| Rect {
                x0: q.left().value,
                y0: h - q.top().value,
                x1: q.right().value,
                y1: h - q.bottom().value,
            });
            let (px_w, px_h) = (
                img.width().ok().unwrap_or(0) as u32,
                img.height().ok().unwrap_or(0) as u32,
            );
            let mut data: Vec<u8> = Vec::new();
            let mut ext: String = String::new();
            if extract_data {
                // 原始流优先；未命中则回退处理位图 → PNG
                if let Ok(raw) = img.get_raw_image_data() {
                    if let Some(e) = sniff_ext(&raw) {
                        data = raw;
                        ext = e.to_string();
                    }
                }
                if data.is_empty() {
                    if let Ok(dyn_img) = img.get_processed_image(doc) {
                        let rgba = dyn_img.to_rgba8();
                        let (bw, bh) = rgba.dimensions();
                        let mut buf: Vec<u8> = Vec::new();
                        {
                            use image::ImageEncoder as _;
                            let enc = image::codecs::png::PngEncoder::new(std::io::BufWriter::new(
                                &mut buf,
                            ));
                            if enc
                                .write_image(&rgba, bw, bh, image::ExtendedColorType::Rgba8)
                                .is_ok()
                            {
                                data = buf;
                                ext = "png".to_string();
                            }
                        }
                    }
                }
            }
            out.push(RawImage {
                data,
                bbox,
                ext,
                px: Some((px_w, px_h)),
                ocr_text: None,
            });
        } else if let Some(form) = obj.as_x_object_form_object() {
            descend(doc, form.iter(), h, depth + 1, extract_data, out);
        }
    }
}

/// `DOCPARSER_OCR_IMAGES=1` → 开嵌入图 OCR（对齐 Python `policy.ocr_images` / bench env）。
fn ocr_images_enabled() -> bool {
    std::env::var("DOCPARSER_OCR_IMAGES").as_deref() == Ok("1")
}

/// OCR 总开关：`DOCPARSER_OCR_ENABLED=0/false` → 关闭（纯文本路径，与 lp OCR-off 同口径）。
/// 默认开启（对齐既有行为：needs_ocr 页自动整页渲染 OCR）。
fn ocr_enabled() -> bool {
    !matches!(
        std::env::var("DOCPARSER_OCR_ENABLED").as_deref(),
        Ok("0") | Ok("false")
    )
}

fn parse_one(pdfium: &Pdfium, path: &str) -> Resp {
    let doc = pdfium
        .load_pdf_from_file(path, None)
        .map_err(|e| classify(&e))?;
    let dpi = 200.0_f32;
    let mut pages = Vec::new();
    let mut render_dir: Option<std::path::PathBuf> = None;
    let mut render_files: Vec<(usize, std::path::PathBuf)> = Vec::new();
    // 嵌入图 OCR 任务：全局序号 → (page_idx, images 内 idx, 临时文件)
    let mut img_dir: Option<std::path::PathBuf> = None;
    let mut img_seq = 0usize;
    let mut img_jobs: Vec<(usize, usize, usize)> = Vec::new();
    let mut img_files: Vec<(usize, std::path::PathBuf)> = Vec::new();
    let ocr_images = ocr_images_enabled();
    let ocr_on = ocr_enabled();
    for (pi, page) in doc.pages().iter().enumerate() {
        let w = page.width().value;
        let h = page.height().value;
        let mut items: Vec<RawTextItem> = Vec::new();
        let mut texts: Vec<String> = Vec::new();
        for obj in page.objects().iter() {
            if obj.as_text_object().is_none() {
                continue;
            }
            let s = obj.as_text_object().unwrap().text();
            if s.trim().is_empty() {
                continue;
            }
            texts.push(s.clone());
            let bbox = obj.bounds().ok().map(|q| Rect {
                x0: q.left().value,
                y0: h - q.top().value, // PDF 左下原点 → 左上原点
                x1: q.right().value,
                y1: h - q.bottom().value,
            });
            items.push(RawTextItem { text: s, bbox });
        }
        let images = collect_page_images(&doc, &page, h, ocr_images);
        // 扫描/稀疏/乱码页：整页渲染（供 OCR 兜底，对应 Python needs_ocr 页）；
        // OCR 总开关关闭时跳过（纯文本路径）
        if ocr_on && page_needs_ocr(&texts) {
            if render_dir.is_none() {
                let d = std::env::temp_dir().join(format!(
                    "docparser_pdf_render_{}_{}",
                    std::process::id(),
                    RENDER_SEQ.fetch_add(1, std::sync::atomic::Ordering::Relaxed),
                ));
                let _ = std::fs::create_dir_all(&d);
                render_dir = Some(d);
            }
            let dir = render_dir.as_ref().unwrap();
            let fn_name = format!("page-{pi:04}.png");
            let out_path = dir.join(&fn_name);
            let wpx = (w * dpi / 72.0).round() as i32;
            let hpx = (h * dpi / 72.0).round() as i32;
            let bitmap = page.render(wpx, hpx, None).map_err(|e| classify(&e));
            if let Ok(bitmap) = bitmap {
                let bw = bitmap.width() as u32;
                let bh = bitmap.height() as u32;
                let rgba = bitmap.as_rgba_bytes();
                use image::ImageEncoder as _;
                let enc = image::codecs::png::PngEncoder::new(std::io::BufWriter::new(
                    std::fs::File::create(&out_path).unwrap(),
                ));
                if enc
                    .write_image(&rgba, bw, bh, image::ExtendedColorType::Rgba8)
                    .is_ok()
                {
                    render_files.push((pi, out_path));
                }
            }
        } else if ocr_on && ocr_images {
            // 非扫描页嵌入图 OCR：needs_ocr 页整页渲染已覆盖图内容，跳过避免重复
            for (ki, im) in images.iter().enumerate() {
                if !ocrable_image(im) {
                    continue;
                }
                if img_dir.is_none() {
                    let d = std::env::temp_dir().join(format!(
                        "docparser_pdf_img_{}_{}",
                        std::process::id(),
                        RENDER_SEQ.fetch_add(1, std::sync::atomic::Ordering::Relaxed),
                    ));
                    let _ = std::fs::create_dir_all(&d);
                    img_dir = Some(d);
                }
                let dir = img_dir.as_ref().unwrap();
                let fn_name = format!("img-{img_seq:05}.{}", im.ext);
                let out_path = dir.join(&fn_name);
                if std::fs::write(&out_path, &im.data).is_ok() {
                    img_files.push((img_seq, out_path));
                    img_jobs.push((pi, ki, img_seq));
                    img_seq += 1;
                }
            }
        }
        pages.push(RawPage {
            name: None,
            items,
            images,
            width: Some(w),
            height: Some(h),
            rotation: None,
            ..Default::default()
        });
    }

    // OCR 回填（needs_ocr 页）：调 docparser-ocr（子进程，模型常驻于其自身）
    let mut any_ocr = false;
    if !render_files.is_empty() {
        if let Some(lines) = run_ocr(render_dir.as_ref().unwrap(), &render_files) {
            let scale = 72.0 / dpi;
            for (pi, items) in lines {
                if let Some(pg) = pages.get_mut(pi) {
                    pg.items = items
                        .into_iter()
                        .map(|(text, quad)| RawTextItem {
                            text,
                            bbox: Some(Rect {
                                x0: quad.iter().map(|p| p[0]).fold(f32::MAX, f32::min) * scale,
                                y0: quad.iter().map(|p| p[1]).fold(f32::MAX, f32::min) * scale,
                                x1: quad.iter().map(|p| p[0]).fold(f32::MIN, f32::max) * scale,
                                y1: quad.iter().map(|p| p[1]).fold(f32::MIN, f32::max) * scale,
                            }),
                        })
                        .collect();
                    any_ocr = true;
                }
            }
        }
    }

    // 嵌入图 OCR 回填（非 needs_ocr 页，opt-in：DOCPARSER_OCR_IMAGES=1）
    if !img_files.is_empty() {
        if let Some(lines) = run_ocr(img_dir.as_ref().unwrap(), &img_files) {
            for (gi, line_items) in lines {
                let Some(&(pi, ki, _)) = img_jobs.iter().find(|(_, _, g)| *g == gi) else {
                    continue;
                };
                let Some(pg) = pages.get_mut(pi) else {
                    continue;
                };
                let Some(im) = pg.images.get_mut(ki) else {
                    continue;
                };
                let ocr: Vec<&str> = line_items
                    .iter()
                    .map(|(s, _)| s.as_str())
                    .filter(|s| !s.trim().is_empty())
                    .collect();
                if !ocr.is_empty() {
                    im.ocr_text = Some(ocr.join("\n"));
                    any_ocr = true;
                }
            }
        }
    }

    // 跨页页眉页脚剔除（多页 stateful，顶/底 7% 边带 + 数字归一化重复）
    let hf = strip_headers_footers(&mut pages);

    let mut raw = RawDoc {
        pages,
        meta: Default::default(),
        needs_ocr: false,
    };
    if !hf.is_empty() {
        raw.meta.insert("headers_footers".into(), hf.join(" | "));
    }
    raw.needs_ocr = !any_ocr
        && raw.pages.iter().all(|p| {
            p.items
                .iter()
                .map(|i| i.text.chars().count())
                .sum::<usize>()
                < 10
        });
    Ok(raw)
}

fn _norm_repeat(text: &str) -> String {
    let mut out = String::with_capacity(text.len());
    let mut last_digit = false;
    for ch in text.chars() {
        if ch.is_ascii_digit() {
            if !last_digit {
                out.push('#');
                last_digit = true;
            }
        } else {
            last_digit = false;
            if !ch.is_whitespace() {
                out.push(ch);
            }
        }
    }
    out
}

/// 剔除在多页顶部/底部窄边带内重复出现的行；返回被剔除的去重文本。
/// 无 bbox / 单页 / 边带外不动作。band = 0.07 页高（与 Python `_strip_headers_footers` 一致）。
fn strip_headers_footers(pages: &mut [RawPage]) -> Vec<String> {
    if pages.len() < 2 {
        return Vec::new();
    }
    let n_with_h = pages.iter().filter(|p| p.height.is_some()).count();
    if n_with_h == 0 {
        return Vec::new();
    }
    let mut removed: Vec<String> = Vec::new();
    for zone in ["top", "bottom"] {
        let mut occ: std::collections::HashMap<String, Vec<(usize, usize)>> =
            std::collections::HashMap::new(); // (page_idx, item_idx)
        for (pi, page) in pages.iter().enumerate() {
            let Some(h) = page.height else { continue };
            let band = if zone == "top" { h * 0.07 } else { h * 0.93 };
            for (ii, it) in page.items.iter().enumerate() {
                let Some(bb) = it.bbox else { continue };
                let hit = if zone == "top" {
                    bb.y1 <= band
                } else {
                    bb.y0 >= band
                };
                if hit {
                    occ.entry(_norm_repeat(&it.text))
                        .or_default()
                        .push((pi, ii));
                }
            }
        }
        for (norm, hits) in occ.iter() {
            if norm.is_empty() {
                continue;
            }
            let mut hit_pages: Vec<usize> = hits.iter().map(|(p, _)| *p).collect();
            hit_pages.sort_unstable();
            hit_pages.dedup();
            if hit_pages.len() >= 2 && hit_pages.len() as f32 >= 0.5 * n_with_h as f32 {
                for (pi, ii) in hits.iter().rev() {
                    pages[*pi].items.remove(*ii);
                }
                if !removed.iter().any(|r| r == norm) {
                    removed.push(norm.clone());
                }
            }
        }
    }
    removed
}

/// 常驻 OCR 引擎（`docparser-ocr serve`，stdin/stdout 行协议，模型只加载一次）。
/// 与 Python `_ResidentEngine` 同一契约：写一行图片路径 → 读一行
/// `{"file":..., "lines":[{box,text,score}...]}`。
struct ResidentOcr {
    child: std::process::Child,
    stdin: std::process::ChildStdin,
    stdout: std::io::BufReader<std::process::ChildStdout>,
}

impl ResidentOcr {
    fn spawn() -> Option<Self> {
        let bin = find_ocr_binary()?;
        let mut cmd = std::process::Command::new(&bin);
        cmd.arg("serve")
            .stdin(std::process::Stdio::piped())
            .stdout(std::process::Stdio::piped())
            .stderr(std::process::Stdio::null());
        if let Some(m) = find_ocr_models() {
            cmd.env("DOCPARSER_OCR_MODELS", m);
        }
        let mut child = cmd.spawn().ok()?;
        let stdin = child.stdin.take()?;
        let stdout = std::io::BufReader::new(child.stdout.take()?);
        Some(Self {
            child,
            stdin,
            stdout,
        })
    }

    fn recognize(&mut self, path: &std::path::Path) -> Option<Vec<serde_json::Value>> {
        use std::io::{BufRead as _, Write as _};
        writeln!(self.stdin, "{}", path.display()).ok()?;
        self.stdin.flush().ok()?;
        let mut line = String::new();
        if self.stdout.read_line(&mut line).ok()? == 0 {
            return None;
        }
        let v: serde_json::Value = serde_json::from_str(&line).ok()?;
        if v.get("error").is_some() {
            return Some(Vec::new());
        }
        Some(
            v.get("lines")
                .and_then(|l| l.as_array())
                .cloned()
                .unwrap_or_default(),
        )
    }
}

static OCR_SERVE: OnceLock<Mutex<Option<ResidentOcr>>> = OnceLock::new();

/// 用常驻引擎识别一批图片；任一环节失败返回 None（调用方回退批量子进程）。
fn serve_ocr(
    files: &[(usize, std::path::PathBuf)],
) -> Option<Vec<(usize, Vec<serde_json::Value>)>> {
    let lock = OCR_SERVE.get_or_init(|| Mutex::new(None));
    let mut guard = lock.lock().ok()?;
    if guard.is_none() {
        *guard = ResidentOcr::spawn();
    }
    let srv = guard.as_mut()?;
    let mut out = Vec::with_capacity(files.len());
    for (key, path) in files {
        match srv.recognize(path) {
            Some(lines) => out.push((*key, lines)),
            None => {
                // 进程异常：丢弃，让调用方回退批量模式
                if let Some(mut dead) = guard.take() {
                    let _ = dead.child.kill();
                }
                return None;
            }
        }
    }
    Some(out)
}

/// OCR 行解析：score ≥0.8 过滤 + 按 min-y 排序 → (text, quad)。
fn lines_from_entries(entries: &[serde_json::Value]) -> Vec<(String, Vec<[f32; 2]>)> {
    let mut items = Vec::new();
    for ent in entries {
        if let Some(s) = ent.get("score") {
            if s.as_f64().unwrap_or(0.0) < 0.8 {
                continue;
            }
        }
        let text = ent
            .get("text")
            .and_then(|t| t.as_str())
            .unwrap_or("")
            .to_string();
        if text.trim().is_empty() {
            continue;
        }
        let mut quad: Vec<[f32; 2]> = Vec::new();
        if let Some(boxes) = ent.get("box").and_then(|b| b.as_array()) {
            for p in boxes {
                let mut pt = [0.0_f32; 2];
                if let (Some(x), Some(y)) = (
                    p.get(0).and_then(|x| x.as_f64()),
                    p.get(1).and_then(|y| y.as_f64()),
                ) {
                    pt = [x as f32, y as f32];
                }
                quad.push(pt);
            }
        }
        items.push((text, quad));
    }
    items.sort_by(|a, b| {
        let ay = a.1.iter().map(|p| p[1]).fold(f32::MAX, f32::min);
        let by = b.1.iter().map(|p| p[1]).fold(f32::MAX, f32::min);
        ay.total_cmp(&by)
    });
    items
}

/// 一行 OCR 结果：文本 + 四边形（图像像素坐标，左上原点）。
type OcrLine = (String, Vec<[f32; 2]>);

/// 一次 OCR 调用的结果：输入序号 → 该页/该图的识别行。
type OcrPageLines = Vec<(usize, Vec<OcrLine>)>;

/// 对渲染出的扫描页/嵌入图批量 OCR：返回 (page_idx, [(text, quad), ...])。
/// quad 为图像像素坐标（左上原点），由调用方换算页面 pt。
/// 优先常驻 serve（模型只加载一次），不可用/失败回退批量子进程。
fn run_ocr(dir: &std::path::Path, files: &[(usize, std::path::PathBuf)]) -> Option<OcrPageLines> {
    if let Some(served) = serve_ocr(files) {
        let mut out = Vec::new();
        for (key, entries) in served {
            let items = lines_from_entries(&entries);
            if !items.is_empty() {
                out.push((key, items));
            }
        }
        return Some(out);
    }
    batch_ocr(dir, files)
}

fn batch_ocr(dir: &std::path::Path, files: &[(usize, std::path::PathBuf)]) -> Option<OcrPageLines> {
    let bin = find_ocr_binary()?;
    let out_json = dir.join("ocr.json");
    let mut cmd = std::process::Command::new(&bin);
    cmd.arg(dir).arg("--out").arg(&out_json);
    if let Some(m) = find_ocr_models() {
        cmd.env("DOCPARSER_OCR_MODELS", m);
    }
    let ok = cmd.output().map(|o| o.status.success()).unwrap_or(false);
    if !ok {
        return None;
    }
    let text = std::fs::read_to_string(&out_json).ok()?;
    let v: serde_json::Value = serde_json::from_str(&text).ok()?;
    let arr = v.as_array()?;
    let mut by_file: std::collections::HashMap<String, Vec<serde_json::Value>> =
        std::collections::HashMap::new();
    for ent in arr {
        if let (Some(f), Some(s)) = (ent.get("file"), ent.get("score")) {
            if s.as_f64().unwrap_or(0.0) >= 0.8 {
                by_file
                    .entry(f.as_str().unwrap_or("").to_string())
                    .or_default()
                    .push(ent.clone());
            }
        }
    }
    let mut out = Vec::new();
    for (pi, fp) in files {
        let key = fp
            .file_name()
            .and_then(|n| n.to_str())
            .unwrap_or("")
            .to_string();
        let Some(entries) = by_file.get(&key) else {
            continue;
        };
        let mut items = Vec::new();
        for ent in entries {
            let text = ent
                .get("text")
                .and_then(|t| t.as_str())
                .unwrap_or("")
                .to_string();
            if text.trim().is_empty() {
                continue;
            }
            let mut quad: Vec<[f32; 2]> = Vec::new();
            if let Some(boxes) = ent.get("box").and_then(|b| b.as_array()) {
                for p in boxes {
                    let mut pt = [0.0_f32; 2];
                    if let (Some(x), Some(y)) = (
                        p.get(0).and_then(|x| x.as_f64()),
                        p.get(1).and_then(|y| y.as_f64()),
                    ) {
                        pt = [x as f32, y as f32];
                    }
                    quad.push(pt);
                }
            }
            items.push((text, quad));
        }
        items.sort_by(|a, b| {
            let ay = a.1.iter().map(|p| p[1]).fold(f32::MAX, f32::min);
            let by = b.1.iter().map(|p| p[1]).fold(f32::MAX, f32::min);
            ay.total_cmp(&by)
        });
        if !items.is_empty() {
            out.push((*pi, items));
        }
    }
    Some(out)
}

/// worker 请求：PDF 路径 + 回包通道。
type WorkerReq = (String, mpsc::Sender<Resp>);

/// worker 发送端（进程内单例持有，长驻线程消费）。
type WorkerTx = Arc<Mutex<mpsc::Sender<WorkerReq>>>;

fn worker_sender() -> Result<WorkerTx> {
    static WORKER: OnceLock<std::result::Result<WorkerTx, String>> = OnceLock::new();
    WORKER
        .get_or_init(|| {
            let file = find_library().ok_or_else(|| {
                "未找到 PDFium 动态库（设 DOCPARSER_PDFIUM_LIB 或安装 pypdfium2）".to_string()
            })?;
            let (tx, rx) = mpsc::channel::<(String, mpsc::Sender<Resp>)>();
            std::thread::Builder::new()
                .name("docparser-pdfium".into())
                .spawn(move || {
                    let lib = file.to_str().ok_or("PDFium 路径非 UTF-8")?.to_string();
                    let bindings = Pdfium::bind_to_library(&lib).map_err(|e| format!("{e}"))?;
                    let pdfium = Pdfium::new(bindings);
                    for (path, resp_tx) in rx.iter() {
                        let _ = resp_tx.send(parse_one(&pdfium, &path));
                    }
                    Ok::<(), String>(())
                })
                .map_err(|e| format!("{e}"))?;
            Ok(Arc::new(Mutex::new(tx)))
        })
        .as_ref()
        .map(Arc::clone)
        .map_err(|m| DocError::corrupt(m.clone()))
}

/// 主后端：PDFium worker（库可用才 available）。
pub struct PdfiumWorkerBackend;

impl ParseCapability for PdfiumWorkerBackend {
    fn id(&self) -> &str {
        "pdfium-worker"
    }
    fn formats(&self) -> &[&str] {
        &["pdf"]
    }
    fn kind(&self) -> BackendKind {
        BackendKind::Bundled
    }
    fn is_available(&self) -> bool {
        find_library().is_some()
    }
    fn parse(&self, path: &str) -> Result<RawDoc> {
        let tx = worker_sender()?
            .lock()
            .map_err(|_| DocError::corrupt("worker 锁"))?
            .clone();
        let (resp_tx, resp_rx) = mpsc::channel();
        tx.send((path.to_string(), resp_tx))
            .map_err(|_| DocError::corrupt("PDFium worker 已退出"))?;
        resp_rx
            .recv()
            .map_err(|_| DocError::corrupt("PDFium worker 无响应"))?
    }
}

/// 兜底后端 v1：pdf-extract（纯 Rust，无 dylib；CJK 无 ToUnicode 局限）。
pub struct PdfTextBackend;

impl ParseCapability for PdfTextBackend {
    fn id(&self) -> &str {
        "pdfium-text-v1"
    }
    fn formats(&self) -> &[&str] {
        &["pdf"]
    }
    fn kind(&self) -> BackendKind {
        BackendKind::Bundled
    }
    fn parse(&self, path: &str) -> Result<RawDoc> {
        let per_page = std::panic::catch_unwind(|| pdf_extract::extract_text_by_pages(path))
            .map_err(|_| {
                DocError::corrupt(
                    "pdf-extract v1 无法解析该 PDF（CJK CID/无 ToUnicode，需 pdfium-worker）",
                )
            })?
            .map_err(|e| {
                let msg = format!("{e}").to_lowercase();
                if msg.contains("password") || msg.contains("encrypt") || msg.contains("permission")
                {
                    DocError::encrypted(format!("PDF 加密或权限受限: {e}"))
                } else {
                    DocError::corrupt(format!("PDF 解析失败: {e}"))
                }
            })?;
        let pages: Vec<RawPage> = per_page
            .into_iter()
            .map(|page_text| RawPage {
                name: None,
                items: page_text
                    .lines()
                    .map(|l| RawTextItem {
                        text: l.to_string(),
                        bbox: None,
                    })
                    .filter(|it| !it.text.trim().is_empty())
                    .collect(),
                ..Default::default()
            })
            .filter(|p| !p.items.is_empty())
            .collect();
        if pages.is_empty() {
            return Err(DocError::corrupt("PDF 无有效文本层"));
        }
        let mut raw = RawDoc {
            pages,
            meta: Default::default(),
            needs_ocr: false,
        };
        raw.needs_ocr = raw.pages.iter().all(|p| {
            p.items
                .iter()
                .map(|i| i.text.chars().count())
                .sum::<usize>()
                < 10
        });
        Ok(raw)
    }
}

// ---------------------------------------------------------------- layout（对照 Python process/layout.py）

/// 行级归一：把逐字/逐词 rect 合并成行级 item（对照 Python `_merge_line_fragments`）。
/// 无 bbox 的项（如 v1 兜底后端）原样保留，排在结果头部。
fn merge_lines(items: Vec<RawTextItem>) -> Vec<RawTextItem> {
    let no_bb: Vec<RawTextItem> = items
        .iter()
        .filter(|it| it.bbox.is_none())
        .cloned()
        .collect();
    let with_bb: Vec<(usize, RawTextItem)> = items
        .into_iter()
        .enumerate()
        .filter(|(_, it)| it.bbox.is_some())
        .collect();
    let mut lines: Vec<Vec<(usize, RawTextItem)>> = Vec::new();
    let mut sorted = with_bb.clone();
    sorted.sort_by(|a, b| {
        a.1.bbox
            .unwrap()
            .y0
            .total_cmp(&b.1.bbox.unwrap().y0)
            .then(a.1.bbox.unwrap().x0.total_cmp(&b.1.bbox.unwrap().x0))
    });
    for ent in &sorted {
        let bb = ent.1.bbox.unwrap();
        let mut placed = false;
        for line in lines.iter_mut() {
            let y0 = line
                .iter()
                .map(|e| e.1.bbox.unwrap().y0)
                .fold(f32::MAX, f32::min);
            let y1 = line
                .iter()
                .map(|e| e.1.bbox.unwrap().y1)
                .fold(f32::MIN, f32::max);
            let ov = (y1.min(bb.y1) - y0.max(bb.y0)).max(0.0);
            if ov > 0.5 * (y1 - y0).min(bb.y1 - bb.y0) {
                line.push(ent.clone());
                placed = true;
                break;
            }
        }
        if !placed {
            lines.push(vec![ent.clone()]);
        }
    }
    let mut out: Vec<RawTextItem> = Vec::new();
    for mut line in lines {
        line.sort_by(|a, b| a.1.bbox.unwrap().x0.total_cmp(&b.1.bbox.unwrap().x0));
        let mut cur: Option<(String, Rect)> = None;
        for (_i, it) in line {
            let bb = it.bbox.unwrap();
            match &mut cur {
                None => cur = Some((it.text.clone(), bb)),
                Some((t, cb)) => {
                    let gap = bb.x0 - cb.x1;
                    let h = (cb.y1 - cb.y0).min(bb.y1 - bb.y0);
                    if gap <= (6.0_f32).max(0.6 * h) {
                        let sep = if gap > 0.2 * h { " " } else { "" };
                        *t = format!("{t}{sep}{}", it.text);
                        *cb = Rect {
                            x0: cb.x0.min(bb.x0),
                            y0: cb.y0.min(bb.y0),
                            x1: cb.x1.max(bb.x1),
                            y1: cb.y1.max(bb.y1),
                        };
                    } else {
                        out.push(RawTextItem {
                            text: std::mem::take(t),
                            bbox: Some(*cb),
                        });
                        cur = Some((it.text.clone(), bb));
                    }
                }
            }
        }
        if let Some((t, cb)) = cur {
            out.push(RawTextItem {
                text: t,
                bbox: Some(cb),
            });
        }
    }
    out.splice(0..0, no_bb); // 无 bbox 项置于头部（顺序即原内容序）
    out
}

fn detect_table(lines: &[RawTextItem]) -> Option<(Vec<Vec<String>>, Vec<bool>)> {
    // y 聚行
    let mut rows: Vec<Vec<RawTextItem>> = Vec::new();
    for it in lines {
        let bb = it.bbox.unwrap();
        let mut placed = false;
        for row in rows.iter_mut() {
            let ry0 = row
                .iter()
                .map(|r| r.bbox.unwrap().y0)
                .fold(f32::MAX, f32::min);
            let ry1 = row
                .iter()
                .map(|r| r.bbox.unwrap().y1)
                .fold(f32::MIN, f32::max);
            let ov = (ry1.min(bb.y1) - ry0.max(bb.y0)).max(0.0);
            if ov > 0.5 * (ry1 - ry0).min(bb.y1 - bb.y0) {
                row.push(it.clone());
                placed = true;
                break;
            }
        }
        if !placed {
            rows.push(vec![it.clone()]);
        }
    }
    rows.sort_by(|a, b| {
        a.iter()
            .map(|r| r.bbox.unwrap().y0)
            .fold(f32::MAX, f32::min)
            .total_cmp(
                &b.iter()
                    .map(|r| r.bbox.unwrap().y0)
                    .fold(f32::MAX, f32::min),
            )
    });
    if rows.len() < 2 {
        return None;
    }
    // x0 聚类（列锚点，容差 8pt）
    let mut xs: Vec<f32> = lines.iter().map(|it| it.bbox.unwrap().x0).collect();
    xs.sort_by(f32::total_cmp);
    let mut anchors: Vec<f32> = Vec::new();
    for x in xs {
        if anchors.is_empty() || x - *anchors.last().unwrap() > 8.0 {
            anchors.push(x);
        }
    }
    if anchors.len() < 3 {
        return None;
    }
    let col_of = |x: f32| -> usize {
        let mut best = 0usize;
        let mut bd = f32::MAX;
        for (i, a) in anchors.iter().enumerate() {
            let d = (x - a).abs();
            if d < bd {
                bd = d;
                best = i;
            }
        }
        best
    };
    let mut grid: Vec<Vec<RawTextItem>> = Vec::new();
    for mut row in rows {
        row.sort_by(|a, b| a.bbox.unwrap().x0.total_cmp(&b.bbox.unwrap().x0));
        let mut merged: Vec<RawTextItem> = Vec::new();
        for it in row {
            let bb = it.bbox.unwrap();
            match merged.last_mut() {
                Some(prev) if col_of(prev.bbox.unwrap().x0) == col_of(bb.x0) => {
                    prev.text = format!("{}{}", prev.text, it.text);
                    let pb = prev.bbox.unwrap();
                    prev.bbox = Some(Rect {
                        x0: pb.x0.min(bb.x0),
                        y0: pb.y0.min(bb.y0),
                        x1: pb.x1.max(bb.x1),
                        y1: pb.y1.max(bb.y1),
                    });
                }
                _ => merged.push(it),
            }
        }
        if merged.len() >= 3 {
            grid.push(merged);
        }
    }
    if grid.len() < 2 {
        return None;
    }
    let counts: Vec<usize> = grid.iter().map(|r| r.len()).collect();
    let modal = counts
        .iter()
        .max_by_key(|c| counts.iter().filter(|x| x == c).count())
        .copied()
        .unwrap_or(0);
    if modal < 3 {
        return None;
    }
    let consistent = counts.iter().filter(|c| **c == modal).count() as f32 / grid.len() as f32;
    if consistent < 0.6 {
        return None;
    }
    let used_keys: Vec<(f32, f32)> = grid
        .iter()
        .flat_map(|r| r.iter())
        .map(|it| {
            let b = it.bbox.unwrap();
            (b.x0, b.y0)
        })
        .collect();
    let used: Vec<bool> = lines
        .iter()
        .map(|it| {
            let b = it.bbox.unwrap();
            used_keys.contains(&(b.x0, b.y0))
        })
        .collect();
    let rows_out: Vec<Vec<String>> = grid
        .into_iter()
        .map(|r| r.into_iter().map(|it| it.text).collect())
        .collect();
    Some((rows_out, used))
}

/// 多栏阅读顺序：x0 聚列（相邻空隙 >6pt 分隔），栏间自左而右、栏内自上而下。
/// 仅当产出 ≥2 栏时重排；否则保持原序。
fn column_order(items: Vec<RawTextItem>) -> Vec<RawTextItem> {
    let mut sorted = items.clone();
    sorted.sort_by(|a, b| {
        let (ax, _ay, ax1) = {
            let r = a.bbox.unwrap();
            (r.x0, r.y0, r.x1)
        };
        let (bx, _by, bx1) = {
            let r = b.bbox.unwrap();
            (r.x0, r.y0, r.x1)
        };
        ax.total_cmp(&bx).then(ax1.total_cmp(&bx1))
    });
    // 列分组（按 x 区间延展）
    let mut cols: Vec<(f32, f32, Vec<RawTextItem>)> = Vec::new();
    for it in sorted {
        let bb = it.bbox.unwrap();
        if let Some(last) = cols.last_mut() {
            if bb.x0 <= last.1 + 6.0 {
                last.1 = last.1.max(bb.x1);
                last.2.push(it);
                continue;
            }
        }
        cols.push((bb.x0, bb.x1, vec![it]));
    }
    if cols.len() < 2 {
        return items; // 单栏：保持原序
    }
    let mut out = Vec::with_capacity(items.len());
    for (_x0, _x1, mut col_items) in cols {
        col_items.sort_by(|a, b| a.bbox.unwrap().y0.total_cmp(&b.bbox.unwrap().y0));
        out.extend(col_items);
    }
    out
}

fn assemble(raw: &RawDoc) -> Document {
    let pages: Vec<Page> = raw
        .pages
        .iter()
        .map(|rp| {
            // ① 行级归一（CJK 逐字 rect → 行级 item）
            let lines = merge_lines(rp.items.clone());
            // ② 表格检测（≥3 列 + ≥60% 行一致性）；有任一无 bbox 项则跳过
            let all_bbox = lines.iter().all(|it| it.bbox.is_some());
            let (table_rows, used, table_rect) =
                match if all_bbox { detect_table(&lines) } else { None } {
                    Some((rows, used)) => {
                        let rect = {
                            let hits: Vec<Rect> = lines
                                .iter()
                                .zip(&used)
                                .filter(|(_, u)| **u)
                                .map(|(it, _)| it.bbox.unwrap())
                                .collect();
                            if hits.is_empty() {
                                None
                            } else {
                                Some(Rect {
                                    x0: hits.iter().map(|r| r.x0).fold(f32::MAX, f32::min),
                                    y0: hits.iter().map(|r| r.y0).fold(f32::MAX, f32::min),
                                    x1: hits.iter().map(|r| r.x1).fold(f32::MIN, f32::max),
                                    y1: hits.iter().map(|r| r.y1).fold(f32::MIN, f32::max),
                                })
                            }
                        };
                        (Some(rows), used, rect)
                    }
                    None => (None, vec![false; lines.len()], None),
                };
            // ③ 剩余段落 → 多栏阅读顺序
            let paras: Vec<RawTextItem> = lines
                .iter()
                .zip(&used)
                .filter(|(_, u)| !**u)
                .map(|(it, _)| it.clone())
                .collect();
            let ordered: Vec<RawTextItem> = if all_bbox { column_order(paras) } else { paras };

            // ④ 块与页文本：段落保持（栏序）顺序；表格按 y0 插入首个更低段落之前
            let mut blocks: Vec<docparser_core::model::Block> = Vec::new();
            if let Some(rows) = &table_rows {
                blocks.push(docparser_core::model::Block {
                    kind: BlockKind::Table,
                    table: Some(docparser_core::model::TableData { rows: rows.clone() }),
                    bbox: table_rect,
                    ..Default::default()
                });
            }
            for it in &ordered {
                blocks.push(docparser_core::model::Block {
                    kind: BlockKind::Paragraph,
                    content: it.text.clone(),
                    bbox: it.bbox,
                    ..Default::default()
                });
            }
            let mut parts: Vec<String> = ordered.iter().map(|it| it.text.clone()).collect();
            if let Some(rows) = &table_rows {
                let ty = table_rect.map(|r| r.y0).unwrap_or(0.0);
                let table_text = rows
                    .iter()
                    .map(|r| r.join(","))
                    .collect::<Vec<_>>()
                    .join("\n");
                // 表格插入到首个 y 更低段落之前；空页/整页表格直接置首
                let mut idx = parts.len();
                for (k, it) in ordered.iter().enumerate() {
                    if it.bbox.map(|r| r.y0).unwrap_or(f32::MAX) > ty {
                        idx = k;
                        break;
                    }
                }
                parts.insert(idx, table_text);
            }
            // ④ 嵌入图 OCR 文本并入页文本（KB 语义：页文本 + "\n" + 图 OCR；有才并入）
            let imgs: Vec<docparser_core::model::Image> = rp
                .images
                .iter()
                .map(|im| docparser_core::model::Image {
                    bbox: im.bbox,
                    ocr_text: im.ocr_text.clone(),
                    ..Default::default()
                })
                .collect();
            for im in &imgs {
                if let Some(t) = &im.ocr_text {
                    if !t.trim().is_empty() {
                        parts.push(t.clone());
                    }
                }
            }
            let text = parts
                .into_iter()
                .filter(|s| !s.trim().is_empty())
                .collect::<Vec<_>>()
                .join("\n");
            Page {
                blocks,
                text,
                images: imgs,
                width: rp.width,
                height: rp.height,
                rotation: rp.rotation,
                ..Default::default()
            }
        })
        .collect();
    Document {
        pages,
        ..Default::default()
    }
}

pub struct PdfPlugin;

impl FormatPlugin for PdfPlugin {
    fn id(&self) -> &str {
        "pdf"
    }
    fn formats(&self) -> &[&str] {
        &["pdf"]
    }
    fn default_parse_chain(&self) -> Vec<&'static str> {
        // worker 优先；worker 缺失或解析失败时回退 v1（encrypted/unsupported 终止码由 engine 处理）
        vec!["pdfium-worker", "pdfium-text-v1"]
    }
    fn default_process_chain(&self) -> Vec<&'static str> {
        vec![]
    }
    fn assemble(&self, raw: &RawDoc) -> Document {
        assemble(raw)
    }
}

/// 注册 PDF 后端（worker 可用才注册；v1 恒可用）与插件。
pub fn register_defaults(reg: &mut Registry) {
    reg.register_parse(Arc::new(PdfTextBackend), None).unwrap();
    if find_library().is_some() {
        reg.register_parse(Arc::new(PdfiumWorkerBackend), None)
            .unwrap();
    }
    reg.register_plugin(Arc::new(PdfPlugin));
}

/// 便于外部核对终止码语义。
pub fn is_terminal(e: &DocError) -> bool {
    matches!(e.code, ErrorCode::Encrypted | ErrorCode::Unsupported)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    #[ignore = "需本机 PDFium 动态库"]
    fn probe_worker_cjk() {
        let p = "/Users/zerojzheng/CODE/hi-agents/documents/docparser/python/bench/corpus/text_plain.pdf";
        match worker_sender() {
            Err(e) => eprintln!("worker init: {e}"),
            Ok(tx) => {
                let tx = tx.lock().unwrap().clone();
                let (rtx, rrx) = mpsc::channel();
                tx.send((p.to_string(), rtx)).unwrap();
                match rrx.recv() {
                    Ok(Ok(raw)) => {
                        let n: usize = raw.pages.iter().map(|pg| pg.items.len()).sum();
                        let s: usize = raw
                            .pages
                            .iter()
                            .flat_map(|pg| &pg.items)
                            .map(|i| i.text.chars().count())
                            .sum();
                        eprintln!("ok: pages={} items={} chars={}", raw.pages.len(), n, s);
                    }
                    Ok(Err(e)) => eprintln!("worker parse err: code={} msg={}", e.code, e.message),
                    Err(e) => eprintln!("channel: {e}"),
                }
            }
        }
    }
}