rsconstruct 0.9.85

use anyhow::{Context, Result};
use std::collections::BTreeMap;
use std::path::{Path, PathBuf};

use serde::{Deserialize, Serialize};

use crate::config::{StandardConfig, output_config_hash, resolve_extra_inputs};
use crate::file_index::FileIndex;
use crate::graph::{BuildGraph, Product};
use crate::processors::Processor;

fn default_ipdfunite_source_dir() -> String {
    "marp/courses".into()
}

fn default_ipdfunite_source_ext() -> String {
    ".md".into()
}

fn default_ipdfunite_source_output_dir() -> String {
    "out/marp".into()
}

#[derive(Debug, Deserialize, Serialize, Clone)]
pub struct IpdfuniteConfig {
    #[serde(default = "default_ipdfunite_source_dir")]
    pub source_dir: String,
    #[serde(default = "default_ipdfunite_source_ext")]
    pub source_ext: String,
    #[serde(default = "default_ipdfunite_source_output_dir")]
    pub source_output_dir: String,
    #[serde(flatten)]
    pub standard: StandardConfig,
}

impl Default for IpdfuniteConfig {
    fn default() -> Self {
        Self {
            source_dir: "marp/courses".into(),
            source_ext: ".md".into(),
            source_output_dir: "out/marp".into(),
            standard: StandardConfig::default(),
        }
    }
}

pub struct IpdfuniteProcessor {
    config: IpdfuniteConfig,
}

impl IpdfuniteProcessor {
    pub const fn new(config: IpdfuniteConfig) -> Self {
        Self { config }
    }

    /// Source files under `source_dir` with the configured extension, grouped
    /// by their containing directory (sorted, so both the directory order and
    /// the merge order within a directory are deterministic).
    ///
    /// Goes through `FileIndex` rather than walking the filesystem: that is
    /// what makes `.rsconstructignore` apply and lets virtual files produced
    /// by an upstream processor be merged. Walking `fs::read_dir` here saw
    /// neither, and re-ran the IO on every fixed-point discovery pass.
    fn source_dirs(&self, file_index: &FileIndex) -> Vec<(PathBuf, Vec<PathBuf>)> {
        let ext = if self.config.source_ext.starts_with('.') {
            self.config.source_ext.clone()
        } else {
            format!(".{}", self.config.source_ext)
        };
        let base = Path::new(&self.config.source_dir);
        let files = file_index.query(base, &[&ext], &[], &[], &[], &[]);

        let mut by_dir: BTreeMap<PathBuf, Vec<PathBuf>> = BTreeMap::new();
        for file in files {
            let dir = crate::processors::parent_dir_or_empty(&file).to_path_buf();
            by_dir.entry(dir).or_default().push(file);
        }
        for files in by_dir.values_mut() {
            files.sort();
        }
        by_dir.into_iter().collect()
    }
}

/// Merge multiple PDF files into a single output using lopdf.
/// Follows the lopdf merge example: renumber objects, collect pages and objects,
/// then assemble a new document with a unified catalog and pages tree.
fn merge_pdfs(inputs: &[PathBuf], output: &Path) -> Result<()> {
    use lopdf::{Document, Object, ObjectId};

    let mut documents: Vec<Document> = Vec::with_capacity(inputs.len());
    for input in inputs {
        let doc = Document::load(input)
            .with_context(|| format!("Failed to load PDF: {}", input.display()))?;
        documents.push(doc);
    }

    let mut max_id = 1;
    let mut documents_pages: BTreeMap<ObjectId, Object> = BTreeMap::new();
    let mut documents_objects: BTreeMap<ObjectId, Object> = BTreeMap::new();
    let mut document = Document::with_version("1.5");

    for mut doc in documents {
        doc.renumber_objects_with(max_id);
        max_id = doc.max_id + 1;

        for object_id in doc.get_pages().into_values() {
            let obj = doc
                .get_object(object_id)
                .with_context(|| {
                    format!(
                        "PDF object {object_id:?} referenced by Pages tree not found in document"
                    )
                })?
                .to_owned();
            documents_pages.insert(object_id, obj);
        }
        documents_objects.extend(doc.objects);
    }

    // Find "Catalog" and "Pages" objects from the collected objects
    let mut catalog_object: Option<(ObjectId, Object)> = None;
    let mut pages_object: Option<(ObjectId, Object)> = None;

    for (object_id, object) in &documents_objects {
        let type_name = object
            .as_dict()
            .ok()
            .and_then(|d| d.get(b"Type").ok())
            .and_then(|t| t.as_name().ok())
            .map(<[u8]>::to_vec);

        match type_name.as_deref() {
            Some(b"Catalog") => {
                catalog_object = Some((*object_id, object.clone()));
            }
            Some(b"Pages") => {
                if let Ok(dictionary) = object.as_dict() {
                    let mut dictionary = dictionary.clone();
                    dictionary.remove(b"Outlines");
                    if let Some((_, ref existing)) = pages_object
                        && let Ok(old_dict) = existing.as_dict()
                    {
                        dictionary.extend(old_dict);
                    }
                    pages_object = Some((
                        pages_object.as_ref().map_or(*object_id, |(id, _)| *id),
                        Object::Dictionary(dictionary),
                    ));
                }
            }
            Some(b"Page") => {}                  // handled separately
            Some(b"Outlines" | b"Outline") => {} // not supported
            _ => {
                document.objects.insert(*object_id, object.clone());
            }
        }
    }

    let catalog_object = catalog_object.context("No PDF Catalog found in input documents")?;
    let pages_object = pages_object.context("No PDF Pages tree found in input documents")?;

    // Set page parents and insert into document
    for (object_id, object) in &documents_pages {
        if let Ok(dictionary) = object.as_dict() {
            let mut dictionary = dictionary.clone();
            dictionary.set("Parent", pages_object.0);
            document
                .objects
                .insert(*object_id, Object::Dictionary(dictionary));
        }
    }

    // Build new Pages object with all kids
    if let Ok(dictionary) = pages_object.1.as_dict() {
        let mut dictionary = dictionary.clone();
        dictionary.set("Count", documents_pages.len() as u32);
        dictionary.set(
            "Kids",
            documents_pages
                .into_keys()
                .map(Object::Reference)
                .collect::<Vec<_>>(),
        );
        document
            .objects
            .insert(pages_object.0, Object::Dictionary(dictionary));
    }

    // Build new Catalog
    if let Ok(dictionary) = catalog_object.1.as_dict() {
        let mut dictionary = dictionary.clone();
        dictionary.set("Pages", pages_object.0);
        dictionary.remove(b"Outlines");
        document
            .objects
            .insert(catalog_object.0, Object::Dictionary(dictionary));
    }

    document.trailer.set("Root", catalog_object.0);
    document.max_id = max_id;
    document.renumber_objects();
    document.adjust_zero_pages();
    if let Some(n) = document.build_outline()
        && let Ok(Object::Dictionary(dict)) = document.get_object_mut(catalog_object.0)
    {
        dict.set("Outlines", Object::Reference(n));
    }
    document.compress();

    document
        .save(output)
        .with_context(|| format!("Failed to write merged PDF: {}", output.display()))?;

    Ok(())
}

impl Processor for IpdfuniteProcessor {
    fn scan_config(&self) -> &crate::config::StandardConfig {
        &self.config.standard
    }

    // Serialize the FULL config (the trait default covers StandardConfig
    // only), so the extra fields reach config-change detection.
    fn config_json(&self) -> Option<String> {
        crate::processors::ProcessorBase::config_json(&self.config)
    }

    fn clean(&self, product: &crate::graph::Product, verbose: bool) -> anyhow::Result<usize> {
        crate::processors::ProcessorBase::clean(product, &product.processor, verbose)
    }

    fn auto_detect(&self, file_index: &FileIndex) -> bool {
        !self.source_dirs(file_index).is_empty()
    }

    fn required_tools(&self) -> Vec<String> {
        Vec::new()
    }

    fn discover(
        &self,
        graph: &mut BuildGraph,
        file_index: &FileIndex,
        instance_name: &str,
    ) -> Result<()> {
        let base = Path::new(&self.config.source_dir);

        let hash = Some(output_config_hash(
            &self.config,
            &crate::config::checksum_fields_of(instance_name),
        ));
        let extra = resolve_extra_inputs(&self.config.standard.dep_inputs)?;

        let upstream_scan_dir = Path::new(&self.config.source_dir)
            .components()
            .next()
            .map(|c| c.as_os_str().to_string_lossy().into_owned())
            .context("source_dir is empty")?;
        let upstream_scan_dirs = [upstream_scan_dir];

        for (dir_path, source_files) in self.source_dirs(file_index) {
            let inputs: Vec<PathBuf> = source_files
                .iter()
                .map(|src| {
                    super::output_path(
                        src,
                        &upstream_scan_dirs,
                        &self.config.source_output_dir,
                        "pdf",
                    )
                })
                .chain(extra.iter().cloned())
                .collect();

            let relative = dir_path.strip_prefix(base).unwrap_or(&dir_path);
            let parent = crate::processors::parent_dir_or_empty(relative);
            let leaf = relative.file_name().with_context(|| {
                format!(
                    "Cannot extract leaf directory name from {}",
                    dir_path.display()
                )
            })?;
            let outputs = vec![
                Path::new(&self.config.standard.output_dir)
                    .join(parent)
                    .join(format!("{}.pdf", leaf.to_string_lossy())),
            ];

            graph.add_product(inputs, outputs, instance_name, hash.clone())?;
        }

        Ok(())
    }

    fn execute(&self, _ctx: &crate::build_context::BuildContext, product: &Product) -> Result<()> {
        let output = product.primary_output();
        crate::processors::ensure_output_dir(output)?;

        let pdf_inputs: Vec<PathBuf> = product
            .inputs
            .iter()
            .filter(|p| p.extension().is_some_and(|e| e == "pdf"))
            .cloned()
            .collect();

        if pdf_inputs.is_empty() {
            anyhow::bail!("No PDF inputs found for {}", output.display());
        }

        merge_pdfs(&pdf_inputs, output)
    }
}

fn plugin_create(toml: &toml::Value) -> anyhow::Result<Box<dyn crate::processors::Processor>> {
    crate::registries::deserialize_and_create(toml, |cfg| Box::new(IpdfuniteProcessor::new(cfg)))
}
inventory::submit! {
    crate::registries::ProcessorPlugin {
        version: 1,
        name: "ipdfunite",
        processor_type: crate::processors::ProcessorType::Generator,
        create: plugin_create,
        fields: &[
            crate::config::FieldSpec { name: "source_dir", ty: crate::config::FieldType::String,
                affects_output: true, required: false,
                doc: "Directory containing course YAML files listing PDFs to merge" },
            crate::config::FieldSpec { name: "source_ext", ty: crate::config::FieldType::String,
                affects_output: true, required: false,
                doc: "Extension of source files used to find PDFs" },
            crate::config::FieldSpec { name: "source_output_dir", ty: crate::config::FieldType::String,
                affects_output: true, required: false,
                doc: "Directory where source PDFs (to be merged) are located" },
        ],
        omit_standard_fields: &["command", "formats", "args"],
        scan_defaults: Some(crate::config::ScanDefaultsData { src_dirs: &[], src_extensions: &["course.yaml"], src_exclude_dirs: &[] }),
        defaults: Some(crate::config::ProcessorDefaults { output_dir: "out/ipdfunite", ..crate::config::ProcessorDefaults::EMPTY }),
        defconfig_json: crate::registries::default_config_json::<IpdfuniteConfig>,
        keywords: &["pdf", "merger", "generator"],
        description: "Merge PDFs from subdirectories into course bundles (in-process)",
        is_native: true,
        can_fix: false,
        supports_batch: false,
        max_jobs_cap: Some(1),
    }
}