car/

export.rs

//! Deterministic export planning for `.car` assets.
//!
//! Planning is intentionally side-effect free: it resolves payload items,
//! computes output identities, sanitizes paths, coalesces canonical sources, and
//! assigns duplicate suffixes without creating directories or writing files.
//! Files avoid reserved facet directories, and duplicate matching ignores ASCII
//! case to keep plans portable across filesystems.

use std::collections::{HashMap, HashSet};
use std::path::{Component, Path, PathBuf};

use crate::car::{CSIItem, Car, ReferenceRect};
use crate::model::Encoding;
use crate::model::rendition::{LayoutType, Rendition};
use crate::output::{self, OutputIdentity};

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ExportFormat {
    Json,
    Png,
    Jpeg,
    Webp,
    Heif,
    Pdf,
    Svg,
    Raw,
}

impl ExportFormat {
    pub fn extension(self) -> &'static str {
        match self {
            Self::Json => "json",
            Self::Png => "png",
            Self::Jpeg => "jpg",
            Self::Webp => "webp",
            Self::Heif => "heic",
            Self::Pdf => "pdf",
            Self::Svg => "svg",
            Self::Raw => "bin",
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ExportSkipReason {
    UnsupportedPayload,
    UnsafeFacetPath,
    UnsafeFileName,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ExportSkip {
    pub facet_name: String,
    pub rendition_name: String,
    pub reason: ExportSkipReason,
}

#[derive(Debug, Clone)]
pub struct ExportJob<'a> {
    pub logical_facet_name: String,
    pub path: PathBuf,
    pub logical_item: &'a CSIItem,
    pub payload_item: &'a CSIItem,
    pub output_identity: OutputIdentity<'a>,
    pub format: ExportFormat,
    pub crops: Vec<ReferenceRect>,
}

#[derive(Debug, Clone)]
pub struct ExportPlan<'a> {
    pub jobs: Vec<ExportJob<'a>>,
    pub skipped: Vec<ExportSkip>,
    pub canonical_coalesced: usize,
}

#[derive(Clone, Copy)]
struct OrderedItem<'a> {
    facet_name: &'a str,
    item: &'a CSIItem,
}

#[derive(Clone)]
struct PlannedItem<'a> {
    logical: OrderedItem<'a>,
    payload: OrderedItem<'a>,
    output_identity: OutputIdentity<'a>,
    crops: Vec<ReferenceRect>,
}

pub fn plan_export<'a>(car: &'a Car, output_root: impl AsRef<Path>) -> ExportPlan<'a> {
    let output_root = output_root.as_ref();
    let ordered_items = collect_ordered_items(car);
    let mut name_counts: HashMap<PathBuf, usize> = HashMap::new();
    let mut assigned_path_keys: HashSet<PathBuf> = HashSet::new();
    let mut directory_path_keys: HashSet<PathBuf> = HashSet::new();
    let mut pending_jobs = Vec::new();
    let mut seen_canonical_outputs: HashSet<Vec<u16>> = HashSet::new();
    let mut jobs = Vec::new();
    let mut skipped = Vec::new();
    let mut canonical_coalesced = 0usize;

    for logical in ordered_items.iter().copied() {
        let Some(planned) = resolve_planned_item(logical, &ordered_items, car) else {
            skipped.push(export_skip(logical, ExportSkipReason::UnsupportedPayload));
            continue;
        };

        if let Some(canonical_key) = planned.output_identity.canonical_identity_key()
            && !seen_canonical_outputs.insert(canonical_key)
        {
            canonical_coalesced += 1;
            continue;
        }

        let Some((path, format)) = build_planned_output_path(output_root, &planned) else {
            skipped.push(export_skip(logical, ExportSkipReason::UnsafeFileName));
            continue;
        };
        // Reserve every directory before assigning file names. Otherwise a later
        // facet could require a directory already assigned to an earlier file.
        for parent in path.ancestors().skip(1) {
            directory_path_keys.insert(output_path_key(parent));
        }
        pending_jobs.push((planned, path, format));
    }

    for (planned, path, format) in pending_jobs {
        let Some(path) = assign_output_path(
            path,
            &mut name_counts,
            &mut assigned_path_keys,
            &directory_path_keys,
        ) else {
            skipped.push(export_skip(
                planned.logical,
                ExportSkipReason::UnsafeFileName,
            ));
            continue;
        };

        jobs.push(ExportJob {
            logical_facet_name: planned.logical.facet_name.to_string(),
            path,
            logical_item: planned.logical.item,
            payload_item: planned.payload.item,
            output_identity: planned.output_identity,
            format,
            crops: planned.crops,
        });
    }

    ExportPlan {
        jobs,
        skipped,
        canonical_coalesced,
    }
}

fn collect_ordered_items(car: &Car) -> Vec<OrderedItem<'_>> {
    let mut ordered_items = Vec::new();
    for (facet_name, facet) in car.named_facets() {
        let Some(items) = car.items_for_facet(facet) else {
            continue;
        };
        ordered_items.extend(items.iter().map(|item| OrderedItem { facet_name, item }));
    }
    ordered_items
}

fn resolve_planned_item<'a>(
    logical: OrderedItem<'a>,
    ordered_items: &[OrderedItem<'a>],
    car: &'a Car,
) -> Option<PlannedItem<'a>> {
    let (payload, crops) = resolve_payload_item(logical, ordered_items, car)?;
    let output_identity =
        car.output_identity_for_payload(logical.facet_name, logical.item, payload.item)?;

    Some(PlannedItem {
        logical,
        payload,
        output_identity,
        crops,
    })
}

fn resolve_payload_item<'a>(
    logical: OrderedItem<'a>,
    ordered_items: &[OrderedItem<'a>],
    car: &'a Car,
) -> Option<(OrderedItem<'a>, Vec<ReferenceRect>)> {
    if output::supported_output_identity(logical.item).is_some() {
        return Some((logical, Vec::new()));
    }

    if !matches!(logical.item.layout(), LayoutType::InternalReference) {
        return None;
    }

    if let Some(resolved) = car.resolve_internal_reference(logical.item) {
        let source = OrderedItem {
            facet_name: logical.facet_name,
            item: resolved.source,
        };
        return Some((source, resolved.crops));
    }

    let fallback = find_same_facet_payload(logical, ordered_items)?;
    Some((fallback, Vec::new()))
}

fn find_same_facet_payload<'a>(
    logical: OrderedItem<'a>,
    ordered_items: &[OrderedItem<'a>],
) -> Option<OrderedItem<'a>> {
    ordered_items.iter().copied().find(|candidate| {
        candidate.facet_name == logical.facet_name
            && !std::ptr::eq(candidate.item, logical.item)
            && candidate.item.name() == logical.item.name()
            && output::supported_output_identity(candidate.item).is_some()
    })
}

fn build_planned_output_path(
    output: &Path,
    planned: &PlannedItem<'_>,
) -> Option<(PathBuf, ExportFormat)> {
    let facet_path = sanitize_relative_path(planned.output_identity.facet_name())?;
    let (format, extension) =
        planned_extension(planned.output_identity.item(), planned.payload.item)?;
    let file_name = if matches!(
        planned.payload.item.header().rendition,
        Some(Rendition::Color(_)) | Some(Rendition::MultisizeImageSet(_))
    ) {
        planned_json_file_name(&planned.output_identity)?
    } else {
        output::suggested_file_name(&planned.output_identity, &extension)?
    };
    Some((output.join(facet_path).join(file_name), format))
}

pub fn sanitize_relative_path(path: &str) -> Option<PathBuf> {
    let mut normalized = PathBuf::new();
    let mut has_component = false;

    for component in Path::new(path).components() {
        match component {
            Component::Normal(part) => {
                normalized.push(part);
                has_component = true;
            }
            Component::CurDir => {}
            Component::ParentDir | Component::RootDir | Component::Prefix(_) => return None,
        }
    }

    has_component.then_some(normalized)
}

fn planned_json_file_name(identity: &OutputIdentity<'_>) -> Option<String> {
    let base_name = output::sanitize_file_name(identity.item().name())?
        .file_name()
        .map(|name| name.to_string_lossy().into_owned())
        .unwrap_or_else(|| String::from("asset"));

    let scale = output::rendition_scale(identity.item());
    let stem = if identity.include_scale_suffix() && scale > 1 {
        let suffix = format!("@{scale}x");
        if base_name.ends_with(&suffix) {
            base_name
        } else {
            format!("{base_name}{suffix}")
        }
    } else {
        base_name
    };

    Some(format!("{stem}.json"))
}

fn planned_extension(
    identity_item: &CSIItem,
    payload_item: &CSIItem,
) -> Option<(ExportFormat, String)> {
    match &payload_item.header().rendition {
        Some(Rendition::Color(_)) | Some(Rendition::MultisizeImageSet(_)) => Some((
            ExportFormat::Json,
            ExportFormat::Json.extension().to_string(),
        )),
        Some(Rendition::RawData(_)) => {
            let format = raw_format(payload_item.header().encoding);
            Some((format, preserved_file_extension(identity_item)?))
        }
        Some(Rendition::ThemeCBCK(_)) if should_save_raw_item(payload_item) => {
            let format = raw_format_for_item(payload_item);
            Some((
                format,
                output::default_raw_extension_for_item(payload_item).to_string(),
            ))
        }
        Some(Rendition::ThemeCBCK(_)) => {
            let (format, extension) = identity_item
                .name()
                .rsplit('.')
                .next()
                .and_then(image_extension)
                .unwrap_or((ExportFormat::Png, "png".to_string()));
            Some((format, extension))
        }
        _ => None,
    }
}

fn preserved_file_extension(item: &CSIItem) -> Option<String> {
    let file_name = output::sanitize_file_name(item.name())?;
    Some(
        file_name
            .extension()
            .map(|extension| extension.to_string_lossy().into_owned())
            .unwrap_or_default(),
    )
}

fn image_extension(extension: &str) -> Option<(ExportFormat, String)> {
    let extension = extension.to_ascii_lowercase();
    match extension.as_str() {
        "png" => Some((ExportFormat::Png, extension)),
        "jpg" | "jpeg" => Some((ExportFormat::Jpeg, extension)),
        "webp" => Some((ExportFormat::Webp, extension)),
        _ => None,
    }
}

fn raw_format(encoding: Encoding) -> ExportFormat {
    match encoding {
        Encoding::HEIF => ExportFormat::Heif,
        Encoding::PDF => ExportFormat::Pdf,
        Encoding::SVG => ExportFormat::Svg,
        Encoding::JPEG => ExportFormat::Jpeg,
        Encoding::WEBP => ExportFormat::Webp,
        _ => ExportFormat::Raw,
    }
}

fn raw_format_for_item(item: &CSIItem) -> ExportFormat {
    if crate::image_conv::is_hevc_compressed(item) {
        ExportFormat::Heif
    } else {
        raw_format(item.header().encoding)
    }
}

pub fn should_save_raw(encoding: Encoding) -> bool {
    matches!(encoding, Encoding::HEIF | Encoding::PDF | Encoding::SVG)
}

pub fn should_save_raw_item(item: &CSIItem) -> bool {
    crate::image_conv::is_hevc_compressed(item) || should_save_raw(item.header().encoding)
}

fn assign_output_path(
    path: PathBuf,
    name_counts: &mut HashMap<PathBuf, usize>,
    assigned_path_keys: &mut HashSet<PathBuf>,
    directory_path_keys: &HashSet<PathBuf>,
) -> Option<PathBuf> {
    let path_key = output_path_key(&path);
    if !assigned_path_keys.contains(&path_key) && !directory_path_keys.contains(&path_key) {
        assigned_path_keys.insert(path_key);
        return Some(path);
    }

    let stem = path.file_stem()?.to_string_lossy().to_string();
    let ext = path
        .extension()
        .map(|ext| ext.to_string_lossy().to_string())
        .unwrap_or_default();
    let parent = path.parent().map(Path::to_path_buf);
    let count = name_counts.entry(path_key).or_insert(0);

    loop {
        *count += 1;
        let new_name = if ext.is_empty() {
            format!("{stem}_{}", *count)
        } else {
            format!("{stem}_{}.{}", *count, ext)
        };
        let candidate = match &parent {
            Some(parent) => parent.join(new_name),
            None => PathBuf::from(new_name),
        };
        let candidate_key = output_path_key(&candidate);
        if !assigned_path_keys.contains(&candidate_key)
            && !directory_path_keys.contains(&candidate_key)
        {
            assigned_path_keys.insert(candidate_key);
            return Some(candidate);
        }
    }
}

fn output_path_key(path: &Path) -> PathBuf {
    PathBuf::from(path.as_os_str().to_ascii_lowercase())
}

fn export_skip(logical: OrderedItem<'_>, reason: ExportSkipReason) -> ExportSkip {
    ExportSkip {
        facet_name: logical.facet_name.to_string(),
        rendition_name: logical.item.name().to_string(),
        reason,
    }
}

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

    #[test]
    fn case_only_directory_names_receive_distinct_output_paths() {
        let mut counts = HashMap::new();
        let mut assigned = HashSet::new();

        let first = assign_output_path(
            "out/Icon/image.png".into(),
            &mut counts,
            &mut assigned,
            &HashSet::new(),
        );
        let second = assign_output_path(
            "out/icon/image.png".into(),
            &mut counts,
            &mut assigned,
            &HashSet::new(),
        );

        assert_eq!(first, Some("out/Icon/image.png".into()));
        assert_eq!(second, Some("out/icon/image_1.png".into()));
    }

    #[test]
    fn case_only_file_names_do_not_reuse_existing_suffixes() {
        let mut counts = HashMap::new();
        let mut assigned = HashSet::new();
        let paths = [
            "out/Icon/image.png",
            "out/Icon/IMAGE_1.PNG",
            "out/Icon/IMAGE.PNG",
            "out/icon/image.png",
        ]
        .map(|path| {
            assign_output_path(path.into(), &mut counts, &mut assigned, &HashSet::new()).unwrap()
        });

        assert_eq!(paths[0], Path::new("out/Icon/image.png"));
        assert_eq!(paths[1], Path::new("out/Icon/IMAGE_1.PNG"));
        assert_eq!(paths[2], Path::new("out/Icon/IMAGE_2.PNG"));
        assert_eq!(paths[3], Path::new("out/icon/image_3.png"));
    }

    #[test]
    fn case_only_names_without_extensions_receive_distinct_output_paths() {
        let mut counts = HashMap::new();
        let mut assigned = HashSet::new();

        assign_output_path(
            "out/Data/Contents".into(),
            &mut counts,
            &mut assigned,
            &HashSet::new(),
        )
        .unwrap();
        let second = assign_output_path(
            "out/data/contents".into(),
            &mut counts,
            &mut assigned,
            &HashSet::new(),
        );

        assert_eq!(second, Some("out/data/contents_1".into()));
    }

    fn assign_paths(paths: &[&str]) -> Vec<PathBuf> {
        let directories = paths
            .iter()
            .flat_map(|path| Path::new(path).ancestors().skip(1))
            .map(output_path_key)
            .collect();
        let mut counts = HashMap::new();
        let mut assigned = HashSet::new();
        paths
            .iter()
            .map(|path| {
                assign_output_path((*path).into(), &mut counts, &mut assigned, &directories)
                    .unwrap()
            })
            .collect()
    }

    #[test]
    fn files_avoid_directories_regardless_of_input_order() {
        let paths = ["out/Icon/image.png", "out/Icon/image.png/image.png"];
        assert_eq!(
            assign_paths(&paths),
            [PathBuf::from("out/Icon/image_1.png"), paths[1].into()]
        );
        assert_eq!(
            assign_paths(&[paths[1], paths[0]]),
            [PathBuf::from(paths[1]), "out/Icon/image_1.png".into()]
        );
    }

    #[test]
    fn numbered_candidates_avoid_case_insensitive_directory_names() {
        assert_eq!(
            assign_paths(&[
                "out/Icon/image.png",
                "out/Icon/IMAGE.PNG/image.png",
                "out/Icon/IMAGE_1.PNG/image.png",
                "out/Icon/IMAGE_2.PNG",
                "out/Icon/image.png",
            ]),
            [
                "out/Icon/image_2.png",
                "out/Icon/IMAGE.PNG/image.png",
                "out/Icon/IMAGE_1.PNG/image.png",
                "out/Icon/IMAGE_2_1.PNG",
                "out/Icon/image_3.png",
            ]
            .map(PathBuf::from)
        );
    }
}