index-core 1.0.0

//! Navigation, bookmark, and session state.

use std::collections::BTreeMap;
use std::fmt::{Display, Formatter};
use std::fs;
use std::path::Path;

use crate::{IndexUrl, Origin, UrlError};

/// Stable identifier for a persisted browsing session.
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct SessionId(String);

impl SessionId {
    /// Creates a session identifier.
    #[must_use]
    pub fn new(input: impl Into<String>) -> Self {
        Self(input.into())
    }

    /// Returns the stored session identifier.
    #[must_use]
    pub fn as_str(&self) -> &str {
        &self.0
    }
}

impl Display for SessionId {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        f.write_str(self.as_str())
    }
}

/// A history entry with redirect information.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct HistoryEntry {
    /// URL the user or caller requested.
    pub requested_url: IndexUrl,
    /// Final URL after redirects.
    pub final_url: IndexUrl,
    /// Redirect hops observed before the final URL.
    pub redirects: Vec<IndexUrl>,
}

impl HistoryEntry {
    /// Creates a history entry without redirects.
    #[must_use]
    pub fn new(url: IndexUrl) -> Self {
        Self {
            requested_url: url.clone(),
            final_url: url,
            redirects: Vec::new(),
        }
    }

    /// Creates a history entry with redirect metadata.
    #[must_use]
    pub fn with_redirects(
        requested_url: IndexUrl,
        final_url: IndexUrl,
        redirects: Vec<IndexUrl>,
    ) -> Self {
        Self {
            requested_url,
            final_url,
            redirects,
        }
    }

    /// Returns the final URL origin.
    #[must_use]
    pub fn origin(&self) -> Option<Origin> {
        self.final_url.origin()
    }
}

/// Browser-like back/forward history.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct HistoryStack {
    back: Vec<HistoryEntry>,
    current: Option<HistoryEntry>,
    forward: Vec<HistoryEntry>,
}

/// Redacted summary of one server response observed during a local session.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ResponseLogEntry {
    /// Monotonic local sequence number.
    pub sequence: u64,
    /// HTTP-like method or semantic source such as `GET` or `POST`.
    pub method: String,
    /// URL requested by the user or form.
    pub requested_url: String,
    /// Final URL reported by the transport.
    pub final_url: String,
    /// MIME type when known.
    pub mime_type: Option<String>,
    /// Redacted body preview.
    pub body_preview: String,
    /// Whether the body preview was truncated.
    pub truncated: bool,
}

impl ResponseLogEntry {
    /// Creates a redacted, bounded response log entry.
    #[must_use]
    pub fn new(
        sequence: u64,
        method: impl Into<String>,
        requested_url: impl AsRef<str>,
        final_url: impl AsRef<str>,
        mime_type: Option<&str>,
        body: &str,
        preview_limit: usize,
    ) -> Self {
        let requested_url = redact_log_text(requested_url.as_ref());
        let final_url = redact_log_text(final_url.as_ref());
        let mime_type = mime_type.map(redact_log_text);
        let redacted_body = redact_log_text(body);
        let (body_preview, truncated) = bounded_preview(&redacted_body, preview_limit);
        Self {
            sequence,
            method: method.into(),
            requested_url,
            final_url,
            mime_type,
            body_preview,
            truncated,
        }
    }

    /// Returns a compact title for sidebar display.
    #[must_use]
    pub fn title(&self) -> String {
        format!("#{} {} {}", self.sequence, self.method, self.final_url)
    }
}

fn bounded_preview(input: &str, limit: usize) -> (String, bool) {
    if limit == 0 {
        return (String::new(), !input.is_empty());
    }
    let mut output = String::new();
    for (count, ch) in input.chars().enumerate() {
        if count >= limit {
            return (output, true);
        }
        output.push(ch);
    }
    (output, false)
}

fn redact_log_text(input: &str) -> String {
    let mut output = String::with_capacity(input.len());
    let mut chars = input.chars().peekable();
    while let Some(ch) = chars.next() {
        output.push(ch);
        if is_sensitive_prefix(&output) {
            while matches!(chars.peek(), Some(' ' | '=' | ':' | '"' | '\'')) {
                if let Some(separator) = chars.next() {
                    output.push(separator);
                }
            }
            while matches!(
                chars.peek(),
                Some(candidate)
                    if !matches!(candidate, '&' | ';' | '\n' | '\r' | '\t' | ' ' | '"' | '\'')
            ) {
                let _ = chars.next();
            }
            output.push_str("[REDACTED]");
        }
    }
    output
}

fn is_sensitive_prefix(input: &str) -> bool {
    let lower = input.to_ascii_lowercase();
    lower.ends_with("authorization")
        || lower.ends_with("cookie")
        || lower.ends_with("set-cookie")
        || lower.ends_with("token")
        || lower.ends_with("password")
        || lower.ends_with("secret")
        || lower.ends_with("api_key")
        || lower.ends_with("apikey")
}

impl HistoryStack {
    /// Creates an empty history stack.
    #[must_use]
    pub fn new() -> Self {
        Self::default()
    }

    /// Visits a URL and clears the forward stack.
    pub fn visit(&mut self, url: IndexUrl) {
        self.visit_entry(HistoryEntry::new(url));
    }

    /// Visits a fully described history entry and clears the forward stack.
    pub fn visit_entry(&mut self, entry: HistoryEntry) {
        if let Some(current) = self.current.take() {
            self.back.push(current);
        }
        self.current = Some(entry);
        self.forward.clear();
    }

    /// Moves one step back and returns the new current entry.
    pub fn go_back(&mut self) -> Option<&HistoryEntry> {
        let previous = self.back.pop()?;
        if let Some(current) = self.current.take() {
            self.forward.push(current);
        }
        self.current = Some(previous);
        self.current.as_ref()
    }

    /// Moves one step forward and returns the new current entry.
    pub fn go_forward(&mut self) -> Option<&HistoryEntry> {
        let next = self.forward.pop()?;
        if let Some(current) = self.current.take() {
            self.back.push(current);
        }
        self.current = Some(next);
        self.current.as_ref()
    }

    /// Returns the current history entry.
    #[must_use]
    pub fn current(&self) -> Option<&HistoryEntry> {
        self.current.as_ref()
    }

    /// Returns whether back navigation is available.
    #[must_use]
    pub fn can_go_back(&self) -> bool {
        !self.back.is_empty()
    }

    /// Returns whether forward navigation is available.
    #[must_use]
    pub fn can_go_forward(&self) -> bool {
        !self.forward.is_empty()
    }

    /// Returns all entries in display order.
    #[must_use]
    pub fn entries(&self) -> Vec<&HistoryEntry> {
        self.back
            .iter()
            .chain(self.current.iter())
            .chain(self.forward.iter().rev())
            .collect()
    }

    /// Returns the current entry index in `entries`.
    #[must_use]
    pub fn current_index(&self) -> Option<usize> {
        self.current.as_ref().map(|_current| self.back.len())
    }

    fn from_entries(
        entries: Vec<HistoryEntry>,
        current_index: Option<usize>,
    ) -> Result<Self, SessionError> {
        let Some(current_index) = current_index else {
            return Ok(Self::new());
        };
        if current_index >= entries.len() {
            return Err(SessionError::Parse(
                "history current index is out of range".to_owned(),
            ));
        }

        let mut back = Vec::new();
        let mut current = None;
        let mut forward = Vec::new();
        for (index, entry) in entries.into_iter().enumerate() {
            if index < current_index {
                back.push(entry);
            } else if index == current_index {
                current = Some(entry);
            } else {
                forward.push(entry);
            }
        }
        forward.reverse();

        Ok(Self {
            back,
            current,
            forward,
        })
    }
}

/// A saved bookmark.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Bookmark {
    /// Human-readable title.
    pub title: String,
    /// Target URL.
    pub url: IndexUrl,
    /// Optional local note for offline research workflows.
    pub note: Option<String>,
    /// Stable local tags for grouping bookmarks.
    pub tags: Vec<String>,
}

/// Bookmark persistence and lookup.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct BookmarkStore {
    bookmarks: BTreeMap<String, Bookmark>,
}

impl BookmarkStore {
    /// Creates an empty bookmark store.
    #[must_use]
    pub fn new() -> Self {
        Self::default()
    }

    /// Adds or replaces a bookmark.
    pub fn add(&mut self, title: impl Into<String>, url: IndexUrl) {
        self.add_with_details(title, url, None, Vec::<String>::new());
    }

    /// Adds or replaces a bookmark with local notes and tags.
    pub fn add_with_details(
        &mut self,
        title: impl Into<String>,
        url: IndexUrl,
        note: Option<String>,
        tags: Vec<String>,
    ) {
        self.bookmarks.insert(
            url.as_str().to_owned(),
            Bookmark {
                title: title.into(),
                url,
                note: note.filter(|note| !note.trim().is_empty()),
                tags: normalized_tags(tags),
            },
        );
    }

    /// Updates notes and tags for an existing bookmark.
    pub fn update_details(
        &mut self,
        url: &IndexUrl,
        note: Option<String>,
        tags: Vec<String>,
    ) -> Option<()> {
        let bookmark = self.bookmarks.get_mut(url.as_str())?;
        bookmark.note = note.filter(|note| !note.trim().is_empty());
        bookmark.tags = normalized_tags(tags);
        Some(())
    }

    /// Removes a bookmark by URL.
    pub fn remove(&mut self, url: &IndexUrl) -> Option<Bookmark> {
        self.bookmarks.remove(url.as_str())
    }

    /// Returns whether the URL is bookmarked.
    #[must_use]
    pub fn contains(&self, url: &IndexUrl) -> bool {
        self.bookmarks.contains_key(url.as_str())
    }

    /// Iterates bookmarks in stable URL order.
    pub fn iter(&self) -> impl Iterator<Item = &Bookmark> {
        self.bookmarks.values()
    }

    /// Saves bookmarks to disk.
    pub fn save_to_path(&self, path: impl AsRef<Path>) -> Result<(), BookmarkError> {
        let mut lines = Vec::new();
        lines.push("index-bookmarks-v1".to_owned());
        for bookmark in self.iter() {
            lines.push(serialized_bookmark_fields(bookmark).join("\t"));
        }
        fs::write(path, lines.join("\n")).map_err(BookmarkError::from)
    }

    /// Loads bookmarks from disk.
    pub fn load_from_path(path: impl AsRef<Path>) -> Result<Self, BookmarkError> {
        let contents = fs::read_to_string(path).map_err(BookmarkError::from)?;
        Self::from_serialized(&contents)
    }

    fn from_serialized(contents: &str) -> Result<Self, BookmarkError> {
        let mut lines = contents.lines();
        if lines.next() != Some("index-bookmarks-v1") {
            return Err(BookmarkError::Parse("missing bookmark header".to_owned()));
        }

        let mut store = Self::new();
        for line in lines {
            if line.is_empty() {
                continue;
            }
            let fields: Vec<&str> = line.split('\t').collect();
            if fields.len() < 2 {
                return Err(BookmarkError::Parse("invalid bookmark record".to_owned()));
            }
            let url = IndexUrl::parse(unescape_field(fields[0]).map_err(BookmarkError::Parse)?)
                .map_err(BookmarkError::Url)?;
            let title = unescape_field(fields[1]).map_err(BookmarkError::Parse)?;
            let note = if fields.len() >= 3 {
                Some(unescape_field(fields[2]).map_err(BookmarkError::Parse)?)
                    .filter(|note| !note.trim().is_empty())
            } else {
                None
            };
            let mut tags = Vec::new();
            for field in &fields[3..] {
                tags.push(unescape_field(field).map_err(BookmarkError::Parse)?);
            }
            store.add_with_details(title, url, note, tags);
        }
        Ok(store)
    }
}

fn serialized_bookmark_fields(bookmark: &Bookmark) -> Vec<String> {
    let mut fields = vec![
        escape_field(bookmark.url.as_str()),
        escape_field(&bookmark.title),
    ];
    if bookmark.note.is_some() || !bookmark.tags.is_empty() {
        fields.push(escape_field(bookmark.note.as_deref().unwrap_or_default()));
        fields.extend(bookmark.tags.iter().map(|tag| escape_field(tag)));
    }
    fields
}

fn normalized_tags(tags: Vec<String>) -> Vec<String> {
    let mut tags = tags
        .into_iter()
        .map(|tag| tag.trim().to_owned())
        .filter(|tag| !tag.is_empty())
        .collect::<Vec<_>>();
    tags.sort();
    tags.dedup();
    tags
}

/// Bookmark persistence errors.
#[derive(Debug)]
pub enum BookmarkError {
    /// Filesystem error.
    Io(std::io::Error),
    /// Serialized data was invalid.
    Parse(String),
    /// Stored URL was invalid.
    Url(UrlError),
}

impl From<std::io::Error> for BookmarkError {
    fn from(value: std::io::Error) -> Self {
        Self::Io(value)
    }
}

impl Display for BookmarkError {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::Io(error) => write!(f, "bookmark IO failed: {error}"),
            Self::Parse(reason) => write!(f, "bookmark data is invalid: {reason}"),
            Self::Url(error) => write!(f, "bookmark URL is invalid: {error}"),
        }
    }
}

impl std::error::Error for BookmarkError {}

/// Durable local knowledge shelf record.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ShelfRecord {
    /// Deterministic shelf identifier.
    pub id: String,
    /// Saved document title.
    pub title: String,
    /// Source URL when known.
    pub source_url: Option<String>,
    /// Transform quality category when known.
    pub quality: Option<String>,
    /// Saved timestamp as deterministic local text.
    pub saved_at: String,
    /// Sorted local tags.
    pub tags: Vec<String>,
    /// Optional local note.
    pub note: Option<String>,
    /// External citation URLs saved with the record.
    pub citations: Vec<String>,
    /// Markdown export path.
    pub markdown_path: String,
    /// JSON export path.
    pub json_path: String,
}

impl ShelfRecord {
    /// Creates a shelf record with a deterministic id.
    #[must_use]
    pub fn new(
        title: impl Into<String>,
        source_url: Option<String>,
        quality: Option<String>,
        saved_at: impl Into<String>,
        citations: Vec<String>,
        markdown_path: impl Into<String>,
        json_path: impl Into<String>,
    ) -> Self {
        let title = title.into();
        let id = shelf_id(&title, source_url.as_deref());
        Self {
            id,
            title,
            source_url,
            quality,
            saved_at: saved_at.into(),
            tags: Vec::new(),
            note: None,
            citations,
            markdown_path: markdown_path.into(),
            json_path: json_path.into(),
        }
    }

    /// Adds a tag, preserving sorted uniqueness.
    pub fn add_tag(&mut self, tag: impl Into<String>) {
        let tag = tag.into();
        if tag.trim().is_empty() || self.tags.iter().any(|existing| existing == &tag) {
            return;
        }
        self.tags.push(tag);
        self.tags.sort();
    }

    /// Replaces the local note.
    pub fn set_note(&mut self, note: impl Into<String>) {
        self.note = Some(note.into());
    }
}

/// Search result for a local knowledge shelf query.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ShelfSearchResult {
    /// Matching shelf record id.
    pub id: String,
    /// Matching shelf record title.
    pub title: String,
    /// Optional source URL.
    pub source_url: Option<String>,
    /// Deterministic rank score.
    pub score: u16,
    /// Fields that matched the query.
    pub matched_fields: Vec<String>,
}

/// Local knowledge shelf store.
#[derive(Debug, Clone, PartialEq, Eq, Default)]
pub struct KnowledgeShelf {
    records: BTreeMap<String, ShelfRecord>,
}

impl KnowledgeShelf {
    /// Creates an empty shelf.
    #[must_use]
    pub fn new() -> Self {
        Self::default()
    }

    /// Inserts or replaces a shelf record.
    pub fn upsert(&mut self, record: ShelfRecord) {
        self.records.insert(record.id.clone(), record);
    }

    /// Returns a shelf record.
    #[must_use]
    pub fn get(&self, id: &str) -> Option<&ShelfRecord> {
        self.records.get(id)
    }

    /// Returns a mutable shelf record.
    pub fn get_mut(&mut self, id: &str) -> Option<&mut ShelfRecord> {
        self.records.get_mut(id)
    }

    /// Iterates records in deterministic id order.
    pub fn iter(&self) -> impl Iterator<Item = &ShelfRecord> {
        self.records.values()
    }

    /// Searches shelf metadata and caller-provided Markdown exports.
    ///
    /// The `markdown_for` callback lets hosts load exported Markdown from local
    /// storage without making `index-core` perform filesystem IO.
    pub fn search<F>(&self, query: &str, mut markdown_for: F) -> Vec<ShelfSearchResult>
    where
        F: FnMut(&ShelfRecord) -> Option<String>,
    {
        let normalized_query = normalize_search_text(query);
        if normalized_query.is_empty() {
            return Vec::new();
        }
        let tokens = normalized_query
            .split_whitespace()
            .map(ToOwned::to_owned)
            .collect::<Vec<_>>();
        let mut results = Vec::new();

        for record in self.iter() {
            let markdown = markdown_for(record).unwrap_or_default();
            if let Some(result) = score_shelf_record(record, &normalized_query, &tokens, &markdown)
            {
                results.push(result);
            }
        }

        results.sort_by(|left, right| {
            right
                .score
                .cmp(&left.score)
                .then_with(|| left.title.cmp(&right.title))
                .then_with(|| left.id.cmp(&right.id))
        });
        results
    }

    /// Saves the shelf to disk.
    pub fn save_to_path(&self, path: impl AsRef<Path>) -> Result<(), ShelfError> {
        let mut lines = vec!["index-shelf-v1".to_owned()];
        for record in self.iter() {
            lines.push(serialized_shelf_record(record).join("\t"));
        }
        fs::write(path, lines.join("\n")).map_err(ShelfError::from)
    }

    /// Loads a shelf from disk. Missing shelves are treated as empty shelves.
    pub fn load_from_path(path: impl AsRef<Path>) -> Result<Self, ShelfError> {
        match fs::read_to_string(path) {
            Ok(contents) => Self::from_serialized(&contents),
            Err(error) if error.kind() == std::io::ErrorKind::NotFound => Ok(Self::new()),
            Err(error) => Err(ShelfError::Io(error.to_string())),
        }
    }

    fn from_serialized(contents: &str) -> Result<Self, ShelfError> {
        let mut lines = contents.lines();
        if lines.next() != Some("index-shelf-v1") {
            return Err(ShelfError::Parse("missing shelf header".to_owned()));
        }
        let mut shelf = Self::new();
        for line in lines {
            if line.is_empty() {
                continue;
            }
            let fields = line.split('\t').collect::<Vec<_>>();
            if fields.len() != 10 {
                return Err(ShelfError::Parse("invalid shelf record".to_owned()));
            }
            let mut record = ShelfRecord {
                id: unescape_field(fields[0]).map_err(ShelfError::Parse)?,
                title: unescape_field(fields[1]).map_err(ShelfError::Parse)?,
                source_url: optional_unescape_field(fields[2])?,
                quality: optional_unescape_field(fields[3])?,
                saved_at: unescape_field(fields[4]).map_err(ShelfError::Parse)?,
                tags: split_list_field(fields[5])?,
                note: optional_unescape_field(fields[6])?,
                citations: split_list_field(fields[7])?,
                markdown_path: unescape_field(fields[8]).map_err(ShelfError::Parse)?,
                json_path: unescape_field(fields[9]).map_err(ShelfError::Parse)?,
            };
            record.tags.sort();
            record.tags.dedup();
            shelf.upsert(record);
        }
        Ok(shelf)
    }
}

fn score_shelf_record(
    record: &ShelfRecord,
    query: &str,
    tokens: &[String],
    markdown: &str,
) -> Option<ShelfSearchResult> {
    let mut score = 0;
    let mut matched_fields = Vec::new();

    score += score_field(
        "title",
        &record.title,
        query,
        tokens,
        60,
        &mut matched_fields,
    );
    if let Some(source_url) = &record.source_url {
        score += score_field(
            "source_url",
            source_url,
            query,
            tokens,
            20,
            &mut matched_fields,
        );
    }
    if !record.tags.is_empty() {
        score += score_field(
            "tags",
            &record.tags.join(" "),
            query,
            tokens,
            50,
            &mut matched_fields,
        );
    }
    if let Some(note) = &record.note {
        score += score_field("note", note, query, tokens, 40, &mut matched_fields);
    }
    if !record.citations.is_empty() {
        score += score_field(
            "citations",
            &record.citations.join(" "),
            query,
            tokens,
            30,
            &mut matched_fields,
        );
    }
    score += score_field(
        "markdown_headings",
        &markdown_headings(markdown),
        query,
        tokens,
        45,
        &mut matched_fields,
    );
    score += score_field("markdown", markdown, query, tokens, 10, &mut matched_fields);

    (score > 0).then(|| ShelfSearchResult {
        id: record.id.clone(),
        title: record.title.clone(),
        source_url: record.source_url.clone(),
        score,
        matched_fields,
    })
}

fn score_field(
    field: &str,
    value: &str,
    query: &str,
    tokens: &[String],
    weight: u16,
    matched_fields: &mut Vec<String>,
) -> u16 {
    if field_matches(value, query, tokens) {
        matched_fields.push(field.to_owned());
        weight
    } else {
        0
    }
}

fn field_matches(value: &str, query: &str, tokens: &[String]) -> bool {
    let value = normalize_search_text(value);
    !value.is_empty() && (value.contains(query) || tokens.iter().all(|token| value.contains(token)))
}

fn markdown_headings(markdown: &str) -> String {
    markdown
        .lines()
        .filter_map(|line| {
            let trimmed = line.trim_start();
            trimmed
                .strip_prefix('#')
                .map(|heading| heading.trim_start_matches('#').trim())
        })
        .filter(|heading| !heading.is_empty())
        .collect::<Vec<_>>()
        .join(" ")
}

fn normalize_search_text(input: &str) -> String {
    input
        .split_whitespace()
        .flat_map(|part| part.chars().flat_map(char::to_lowercase).chain([' ']))
        .collect::<String>()
        .trim_end()
        .to_owned()
}

fn shelf_id(title: &str, source_url: Option<&str>) -> String {
    let mut hash: u64 = 0xcbf29ce484222325;
    for byte in source_url.unwrap_or("").bytes().chain(title.bytes()) {
        hash ^= u64::from(byte);
        hash = hash.wrapping_mul(0x100000001b3);
    }
    format!("shelf-{hash:016x}")
}

fn serialized_shelf_record(record: &ShelfRecord) -> Vec<String> {
    vec![
        escape_field(&record.id),
        escape_field(&record.title),
        record
            .source_url
            .as_ref()
            .map_or_else(String::new, |value| escape_field(value)),
        record
            .quality
            .as_ref()
            .map_or_else(String::new, |value| escape_field(value)),
        escape_field(&record.saved_at),
        join_list_field(&record.tags),
        record
            .note
            .as_ref()
            .map_or_else(String::new, |value| escape_field(value)),
        join_list_field(&record.citations),
        escape_field(&record.markdown_path),
        escape_field(&record.json_path),
    ]
}

fn optional_unescape_field(field: &str) -> Result<Option<String>, ShelfError> {
    if field.is_empty() {
        Ok(None)
    } else {
        Ok(Some(unescape_field(field).map_err(ShelfError::Parse)?))
    }
}

fn join_list_field(values: &[String]) -> String {
    values
        .iter()
        .map(|value| escape_field(value))
        .collect::<Vec<_>>()
        .join(",")
}

fn split_list_field(field: &str) -> Result<Vec<String>, ShelfError> {
    if field.is_empty() {
        return Ok(Vec::new());
    }
    field
        .split(',')
        .map(|value| unescape_field(value).map_err(ShelfError::Parse))
        .collect()
}

/// Knowledge shelf persistence errors.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ShelfError {
    /// Filesystem failure.
    Io(String),
    /// Parse failure.
    Parse(String),
}

impl From<std::io::Error> for ShelfError {
    fn from(value: std::io::Error) -> Self {
        Self::Io(value.to_string())
    }
}

impl Display for ShelfError {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::Io(error) => write!(f, "shelf IO failed: {error}"),
            Self::Parse(error) => write!(f, "shelf parse failed: {error}"),
        }
    }
}

impl std::error::Error for ShelfError {}

/// Per-origin browsing state.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct OriginState {
    /// Number of visits recorded for this origin.
    pub visits: u64,
    /// Last final URL observed for this origin.
    pub last_url: Option<IndexUrl>,
}

impl OriginState {
    /// Records a visit for this origin.
    pub fn record_visit(&mut self, url: IndexUrl) {
        self.visits = self.visits.saturating_add(1);
        self.last_url = Some(url);
    }
}

/// Persisted sidebar mode preference for a browsing session.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum SessionSidebarMode {
    /// Sidebar lists page links.
    #[default]
    Links,
    /// Sidebar lists headings and page regions.
    Outline,
    /// Sidebar lists forms and actions.
    Forms,
    /// Sidebar lists semantic page regions.
    Regions,
    /// Sidebar lists the latest search results.
    Search,
    /// Sidebar lists local redacted response logs.
    Logs,
}

impl SessionSidebarMode {
    /// Returns the stable serialized mode name.
    #[must_use]
    pub const fn as_str(self) -> &'static str {
        match self {
            Self::Links => "links",
            Self::Outline => "outline",
            Self::Forms => "forms",
            Self::Regions => "regions",
            Self::Search => "search",
            Self::Logs => "logs",
        }
    }

    /// Parses a persisted sidebar mode.
    pub fn parse(input: &str) -> Option<Self> {
        match input {
            "links" => Some(Self::Links),
            "outline" => Some(Self::Outline),
            "forms" => Some(Self::Forms),
            "regions" => Some(Self::Regions),
            "search" => Some(Self::Search),
            "logs" => Some(Self::Logs),
            _ => None,
        }
    }

    /// Returns the next sidebar mode.
    #[must_use]
    pub const fn next(self) -> Self {
        match self {
            Self::Links => Self::Outline,
            Self::Outline => Self::Forms,
            Self::Forms => Self::Regions,
            Self::Regions => Self::Search,
            Self::Search => Self::Logs,
            Self::Logs => Self::Links,
        }
    }

    /// Returns the previous sidebar mode.
    #[must_use]
    pub const fn previous(self) -> Self {
        match self {
            Self::Links => Self::Logs,
            Self::Logs => Self::Search,
            Self::Outline => Self::Links,
            Self::Forms => Self::Outline,
            Self::Regions => Self::Forms,
            Self::Search => Self::Regions,
        }
    }
}

impl Display for SessionSidebarMode {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        f.write_str(self.as_str())
    }
}

/// Persisted reader profile preference for terminal presentation.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum ReaderProfile {
    /// Balanced reading defaults.
    #[default]
    Reader,
    /// Documentation-oriented emphasis for headings, tables, and code.
    Docs,
    /// Link-forward emphasis for navigation-heavy pages.
    Links,
    /// Research emphasis for quotes, references, and diagnostics.
    Research,
    /// Dense presentation for small terminals.
    Compact,
    /// More explicit visual cues for structure and status.
    Verbose,
}

impl ReaderProfile {
    /// Returns the stable serialized profile name.
    #[must_use]
    pub const fn as_str(self) -> &'static str {
        match self {
            Self::Reader => "reader",
            Self::Docs => "docs",
            Self::Links => "links",
            Self::Research => "research",
            Self::Compact => "compact",
            Self::Verbose => "verbose",
        }
    }

    /// Parses a persisted reader profile.
    pub fn parse(input: &str) -> Option<Self> {
        match input {
            "reader" => Some(Self::Reader),
            "docs" => Some(Self::Docs),
            "links" => Some(Self::Links),
            "research" => Some(Self::Research),
            "compact" => Some(Self::Compact),
            "verbose" => Some(Self::Verbose),
            _ => None,
        }
    }

    /// Returns all stable profile variants in display order.
    #[must_use]
    pub const fn all() -> [Self; 6] {
        [
            Self::Reader,
            Self::Docs,
            Self::Links,
            Self::Research,
            Self::Compact,
            Self::Verbose,
        ]
    }
}

impl Display for ReaderProfile {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        f.write_str(self.as_str())
    }
}

/// Persisted terminal UI state for a browsing session.
#[derive(Debug, Clone, PartialEq, Eq, Default)]
pub struct SessionUiState {
    /// Last selected sidebar mode.
    pub sidebar_mode: SessionSidebarMode,
    /// Last selected reader profile.
    pub reader_profile: ReaderProfile,
    /// Whether the profile was selected explicitly by the user.
    pub reader_profile_manual: bool,
}

/// Complete persisted browsing session state.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct SessionState {
    /// Session identifier.
    pub id: SessionId,
    /// Back/forward navigation state.
    pub history: HistoryStack,
    /// Saved bookmarks.
    pub bookmarks: BookmarkStore,
    /// Per-origin state.
    pub origins: BTreeMap<Origin, OriginState>,
    /// Persisted terminal UI preferences.
    pub ui: SessionUiState,
}

impl SessionState {
    /// Creates an empty session.
    #[must_use]
    pub fn new(id: SessionId) -> Self {
        Self {
            id,
            history: HistoryStack::new(),
            bookmarks: BookmarkStore::new(),
            origins: BTreeMap::new(),
            ui: SessionUiState::default(),
        }
    }

    /// Visits a URL in this session.
    pub fn visit(&mut self, url: IndexUrl) {
        self.visit_entry(HistoryEntry::new(url));
    }

    /// Visits a history entry in this session.
    pub fn visit_entry(&mut self, entry: HistoryEntry) {
        if let Some(origin) = entry.origin() {
            self.origins
                .entry(origin)
                .or_default()
                .record_visit(entry.final_url.clone());
        }
        self.history.visit_entry(entry);
    }

    /// Moves one step back.
    pub fn go_back(&mut self) -> Option<&HistoryEntry> {
        self.history.go_back()
    }

    /// Moves one step forward.
    pub fn go_forward(&mut self) -> Option<&HistoryEntry> {
        self.history.go_forward()
    }

    /// Bookmarks the current page when one is loaded.
    pub fn bookmark_current(&mut self, title: impl Into<String>) -> Option<()> {
        let url = self.history.current()?.final_url.clone();
        self.bookmarks.add(title, url);
        Some(())
    }

    /// Serializes the session to a deterministic text representation.
    #[must_use]
    pub fn serialize(&self) -> String {
        let mut lines = Vec::new();
        lines.push("index-session-v1".to_owned());
        lines.push(format!("id\t{}", escape_field(self.id.as_str())));
        lines.push(format!(
            "ui\t{}\t{}\t{}",
            self.ui.sidebar_mode.as_str(),
            self.ui.reader_profile.as_str(),
            if self.ui.reader_profile_manual {
                "manual"
            } else {
                "auto"
            }
        ));
        if let Some(current_index) = self.history.current_index() {
            lines.push(format!("history\t{current_index}"));
        } else {
            lines.push("history\tnone".to_owned());
        }
        for entry in self.history.entries() {
            let mut fields = vec![
                "entry".to_owned(),
                escape_field(entry.requested_url.as_str()),
                escape_field(entry.final_url.as_str()),
            ];
            fields.extend(entry.redirects.iter().map(|url| escape_field(url.as_str())));
            lines.push(fields.join("\t"));
        }
        for bookmark in self.bookmarks.iter() {
            let mut fields = vec!["bookmark".to_owned()];
            fields.extend(serialized_bookmark_fields(bookmark));
            lines.push(fields.join("\t"));
        }
        for (origin, state) in &self.origins {
            let last_url = state
                .last_url
                .as_ref()
                .map_or_else(String::new, |url| escape_field(url.as_str()));
            lines.push(format!(
                "origin\t{}\t{}\t{}",
                escape_field(origin.as_str()),
                state.visits,
                last_url
            ));
        }
        lines.join("\n")
    }

    /// Deserializes a saved session.
    pub fn deserialize(contents: &str) -> Result<Self, SessionError> {
        let mut lines = contents.lines();
        if lines.next() != Some("index-session-v1") {
            return Err(SessionError::Parse("missing session header".to_owned()));
        }

        let mut id = None;
        let mut current_index = None;
        let mut entries = Vec::new();
        let mut bookmarks = BookmarkStore::new();
        let mut origins = BTreeMap::new();
        let mut ui = SessionUiState::default();

        for line in lines {
            if line.is_empty() {
                continue;
            }
            let fields: Vec<&str> = line.split('\t').collect();
            match fields.first().copied() {
                Some("id") if fields.len() == 2 => {
                    id = Some(SessionId::new(
                        unescape_field(fields[1]).map_err(SessionError::Parse)?,
                    ));
                }
                Some("history") if fields.len() == 2 => {
                    current_index = parse_history_index(fields[1])?;
                }
                Some("ui") if (2..=4).contains(&fields.len()) => {
                    let mode = SessionSidebarMode::parse(fields[1])
                        .ok_or_else(|| SessionError::Parse("invalid sidebar mode".to_owned()))?;
                    ui.sidebar_mode = mode;
                    if fields.len() == 3 {
                        ui.reader_profile = ReaderProfile::parse(fields[2]).ok_or_else(|| {
                            SessionError::Parse("invalid reader profile".to_owned())
                        })?;
                        ui.reader_profile_manual = true;
                    } else if fields.len() == 4 {
                        ui.reader_profile = ReaderProfile::parse(fields[2]).ok_or_else(|| {
                            SessionError::Parse("invalid reader profile".to_owned())
                        })?;
                        ui.reader_profile_manual = match fields[3] {
                            "auto" => false,
                            "manual" => true,
                            _ => {
                                return Err(SessionError::Parse(
                                    "invalid reader profile mode".to_owned(),
                                ));
                            }
                        };
                    }
                }
                Some("entry") if fields.len() >= 3 => {
                    let requested_url = parse_session_url(fields[1])?;
                    let final_url = parse_session_url(fields[2])?;
                    let mut redirects = Vec::new();
                    for field in &fields[3..] {
                        redirects.push(parse_session_url(field)?);
                    }
                    entries.push(HistoryEntry::with_redirects(
                        requested_url,
                        final_url,
                        redirects,
                    ));
                }
                Some("bookmark") if fields.len() >= 3 => {
                    let url = parse_session_url(fields[1])?;
                    let title = unescape_field(fields[2]).map_err(SessionError::Parse)?;
                    let note = if fields.len() >= 4 {
                        Some(unescape_field(fields[3]).map_err(SessionError::Parse)?)
                            .filter(|note| !note.trim().is_empty())
                    } else {
                        None
                    };
                    let mut tags = Vec::new();
                    for field in &fields[4..] {
                        tags.push(unescape_field(field).map_err(SessionError::Parse)?);
                    }
                    bookmarks.add_with_details(title, url, note, tags);
                }
                Some("origin") if fields.len() == 4 => {
                    let origin = Origin::from_stored(
                        unescape_field(fields[1]).map_err(SessionError::Parse)?,
                    );
                    let visits = fields[2]
                        .parse::<u64>()
                        .map_err(|error| SessionError::Parse(error.to_string()))?;
                    let last_url = if fields[3].is_empty() {
                        None
                    } else {
                        Some(parse_session_url(fields[3])?)
                    };
                    origins.insert(origin, OriginState { visits, last_url });
                }
                _ => return Err(SessionError::Parse("invalid session record".to_owned())),
            }
        }

        let id = id.ok_or_else(|| SessionError::Parse("missing session id".to_owned()))?;
        let history = HistoryStack::from_entries(entries, current_index)?;
        Ok(Self {
            id,
            history,
            bookmarks,
            origins,
            ui,
        })
    }

    /// Saves the session to disk.
    pub fn save_to_path(&self, path: impl AsRef<Path>) -> Result<(), SessionError> {
        fs::write(path, self.serialize()).map_err(SessionError::from)
    }

    /// Loads a session from disk.
    pub fn load_from_path(path: impl AsRef<Path>) -> Result<Self, SessionError> {
        let contents = fs::read_to_string(path).map_err(SessionError::from)?;
        Self::deserialize(&contents)
    }
}

/// Session persistence errors.
#[derive(Debug)]
pub enum SessionError {
    /// Filesystem error.
    Io(std::io::Error),
    /// Serialized data was invalid.
    Parse(String),
    /// Stored URL was invalid.
    Url(UrlError),
}

impl From<std::io::Error> for SessionError {
    fn from(value: std::io::Error) -> Self {
        Self::Io(value)
    }
}

impl Display for SessionError {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::Io(error) => write!(f, "session IO failed: {error}"),
            Self::Parse(reason) => write!(f, "session data is invalid: {reason}"),
            Self::Url(error) => write!(f, "session URL is invalid: {error}"),
        }
    }
}

impl std::error::Error for SessionError {}

fn parse_history_index(input: &str) -> Result<Option<usize>, SessionError> {
    if input == "none" {
        Ok(None)
    } else {
        input
            .parse::<usize>()
            .map(Some)
            .map_err(|error| SessionError::Parse(error.to_string()))
    }
}

fn parse_session_url(input: &str) -> Result<IndexUrl, SessionError> {
    let unescaped = unescape_field(input).map_err(SessionError::Parse)?;
    IndexUrl::parse(unescaped).map_err(SessionError::Url)
}

fn escape_field(input: &str) -> String {
    let mut escaped = String::with_capacity(input.len());
    for ch in input.chars() {
        match ch {
            '\\' => escaped.push_str("\\\\"),
            '\t' => escaped.push_str("\\t"),
            '\n' => escaped.push_str("\\n"),
            '\r' => escaped.push_str("\\r"),
            _ => escaped.push(ch),
        }
    }
    escaped
}

fn unescape_field(input: &str) -> Result<String, String> {
    let mut unescaped = String::with_capacity(input.len());
    let mut chars = input.chars();
    while let Some(ch) = chars.next() {
        if ch != '\\' {
            unescaped.push(ch);
            continue;
        }

        let Some(next) = chars.next() else {
            return Err("dangling escape".to_owned());
        };
        match next {
            '\\' => unescaped.push('\\'),
            't' => unescaped.push('\t'),
            'n' => unescaped.push('\n'),
            'r' => unescaped.push('\r'),
            other => return Err(format!("unknown escape: {other}")),
        }
    }
    Ok(unescaped)
}

#[cfg(test)]
mod tests {
    use std::time::{SystemTime, UNIX_EPOCH};

    use super::{
        BookmarkStore, HistoryEntry, HistoryStack, KnowledgeShelf, OriginState, ReaderProfile,
        ResponseLogEntry, SessionId, SessionSidebarMode, SessionState, ShelfError, ShelfRecord,
    };
    use crate::{IndexUrl, Origin};

    #[test]
    fn history_supports_back_and_forward_navigation() -> Result<(), Box<dyn std::error::Error>> {
        let first = IndexUrl::parse("https://example.com/one")?;
        let second = IndexUrl::parse("https://example.com/two")?;
        let third = IndexUrl::parse("https://example.com/three")?;
        let mut history = HistoryStack::new();

        history.visit(first.clone());
        history.visit(second.clone());
        history.visit(third);

        assert_eq!(
            history.go_back().map(|entry| &entry.final_url),
            Some(&second)
        );
        assert_eq!(
            history.go_back().map(|entry| &entry.final_url),
            Some(&first)
        );
        assert!(history.go_back().is_none());
        assert_eq!(
            history.go_forward().map(|entry| &entry.final_url),
            Some(&second)
        );
        Ok(())
    }

    #[test]
    fn visiting_new_url_clears_forward_history() -> Result<(), Box<dyn std::error::Error>> {
        let first = IndexUrl::parse("https://example.com/one")?;
        let second = IndexUrl::parse("https://example.com/two")?;
        let third = IndexUrl::parse("https://example.com/three")?;
        let mut history = HistoryStack::new();

        history.visit(first);
        history.visit(second);
        assert!(history.go_back().is_some());
        history.visit(third);

        assert!(!history.can_go_forward());
        Ok(())
    }

    #[test]
    fn response_log_entries_redact_and_bound_server_body() {
        let entry = ResponseLogEntry::new(
            7,
            "POST",
            "https://example.com/login?token=secret-token&next=/home",
            "https://example.com/home",
            Some("text/html"),
            "Welcome token=abc123 password=hunter2 visible text",
            28,
        );

        assert_eq!(entry.sequence, 7);
        assert!(entry.requested_url.contains("token=[REDACTED]"));
        assert!(!entry.requested_url.contains("secret-token"));
        assert!(!entry.body_preview.contains("abc123"));
        assert!(!entry.body_preview.contains("hunter2"));
        assert!(entry.body_preview.chars().count() <= 28);
        assert!(entry.truncated);
        assert!(entry.title().contains("POST"));
    }

    #[test]
    fn bookmarks_persist_to_disk() -> Result<(), Box<dyn std::error::Error>> {
        let path = temp_path("bookmarks");
        let mut store = BookmarkStore::new();
        let url = IndexUrl::parse("https://example.com/docs")?;
        store.add_with_details(
            "Docs\tIndex",
            url.clone(),
            Some("Read before release".to_owned()),
            vec!["rust".to_owned(), "docs".to_owned(), "rust".to_owned()],
        );

        store.save_to_path(&path)?;
        let restored = BookmarkStore::load_from_path(&path)?;
        std::fs::remove_file(&path)?;

        assert!(restored.contains(&url));
        assert_eq!(
            restored
                .iter()
                .next()
                .map(|bookmark| bookmark.title.as_str()),
            Some("Docs\tIndex")
        );
        let bookmark = restored.iter().next().ok_or("missing bookmark")?;
        assert_eq!(bookmark.note.as_deref(), Some("Read before release"));
        assert_eq!(bookmark.tags, vec!["docs".to_owned(), "rust".to_owned()]);
        Ok(())
    }

    #[test]
    fn bookmark_details_can_be_updated() -> Result<(), Box<dyn std::error::Error>> {
        let mut store = BookmarkStore::new();
        let url = IndexUrl::parse("https://example.com/docs")?;
        store.add("Docs", url.clone());

        assert_eq!(
            store.update_details(
                &url,
                Some("Updated".to_owned()),
                vec!["research".to_owned(), "docs".to_owned()],
            ),
            Some(())
        );

        let bookmark = store.iter().next().ok_or("missing bookmark")?;
        assert_eq!(bookmark.note.as_deref(), Some("Updated"));
        assert_eq!(
            bookmark.tags,
            vec!["docs".to_owned(), "research".to_owned()]
        );
        Ok(())
    }

    #[test]
    fn shelf_ids_are_deterministic_and_records_roundtrip() -> Result<(), Box<dyn std::error::Error>>
    {
        let path = temp_path("shelf");
        let mut record = ShelfRecord::new(
            "Index Guide",
            Some("https://example.org/guide".to_owned()),
            Some("strong-generic".to_owned()),
            "12345",
            vec!["https://example.org/cite".to_owned()],
            "exports/index-guide.md",
            "exports/index-guide.json",
        );
        let same = ShelfRecord::new(
            "Index Guide",
            Some("https://example.org/guide".to_owned()),
            None,
            "later",
            Vec::new(),
            "a.md",
            "a.json",
        );
        assert_eq!(record.id, same.id);

        record.add_tag("docs");
        record.add_tag("rust");
        record.add_tag("docs");
        record.set_note("Keep for packaging");
        let mut shelf = KnowledgeShelf::new();
        shelf.upsert(record.clone());
        shelf.save_to_path(&path)?;

        let restored = KnowledgeShelf::load_from_path(&path)?;
        let restored_record = restored.get(&record.id).ok_or("missing shelf record")?;
        assert_eq!(restored_record.title, "Index Guide");
        assert_eq!(
            restored_record.tags,
            vec!["docs".to_owned(), "rust".to_owned()]
        );
        assert_eq!(restored_record.note.as_deref(), Some("Keep for packaging"));
        std::fs::remove_file(&path)?;
        Ok(())
    }

    #[test]
    fn missing_shelf_loads_as_empty() -> Result<(), Box<dyn std::error::Error>> {
        let path = temp_path("missing-shelf");
        let shelf = KnowledgeShelf::load_from_path(&path)?;
        assert_eq!(shelf.iter().count(), 0);
        Ok(())
    }

    #[test]
    fn shelf_loader_rejects_invalid_records() {
        assert_eq!(
            KnowledgeShelf::from_serialized("bad").map(|_| ()),
            Err(ShelfError::Parse("missing shelf header".to_owned()))
        );
        assert_eq!(
            KnowledgeShelf::from_serialized("index-shelf-v1\nonly-one-field").map(|_| ()),
            Err(ShelfError::Parse("invalid shelf record".to_owned()))
        );
        assert!(
            KnowledgeShelf::from_serialized(
                "index-shelf-v1\nid\\\ttitle\t\t\t123\t\t\t\tout.md\tout.json"
            )
            .is_err()
        );
        assert_eq!(
            ShelfError::Parse("bad field".to_owned()).to_string(),
            "shelf parse failed: bad field"
        );
    }

    #[test]
    fn shelf_search_ranks_metadata_and_markdown_matches() {
        let mut rust = ShelfRecord::new(
            "Rust Guide",
            Some("https://example.org/rust".to_owned()),
            Some("strong-generic".to_owned()),
            "1",
            vec!["https://example.org/citation".to_owned()],
            "rust.md",
            "rust.json",
        );
        rust.add_tag("docs");
        rust.set_note("ownership and borrowing");
        let rust_id = rust.id.clone();

        let mut archive = ShelfRecord::new(
            "Archive Notes",
            Some("https://example.org/archive".to_owned()),
            None,
            "2",
            Vec::new(),
            "archive.md",
            "archive.json",
        );
        archive.set_note("release history");

        let mut shelf = KnowledgeShelf::new();
        shelf.upsert(archive);
        shelf.upsert(rust);

        let results = shelf.search("ownership", |record| {
            (record.id == rust_id).then(|| "# Ownership\nDetailed notes".to_owned())
        });

        assert_eq!(results.len(), 1);
        assert_eq!(results[0].title, "Rust Guide");
        assert!(results[0].score > 40);
        assert!(results[0].matched_fields.contains(&"note".to_owned()));
        assert!(
            results[0]
                .matched_fields
                .contains(&"markdown_headings".to_owned())
        );

        let empty = shelf.search("   ", |_| None);
        assert!(empty.is_empty());
    }

    #[test]
    fn shelf_search_matches_non_english_titles_notes_tags_and_headings() {
        let mut spanish = ShelfRecord::new(
            "Índice Público",
            Some("https://example.org/es".to_owned()),
            Some("strong-generic".to_owned()),
            "1",
            Vec::new(),
            "es.md",
            "es.json",
        );
        spanish.add_tag("manuales");
        spanish.set_note("Navegación tranquila");
        let spanish_id = spanish.id.clone();

        let arabic = ShelfRecord::new(
            "فهرس المعرفة",
            Some("https://example.org/ar".to_owned()),
            Some("strong-generic".to_owned()),
            "2",
            Vec::new(),
            "ar.md",
            "ar.json",
        );
        let arabic_id = arabic.id.clone();

        let cjk = ShelfRecord::new(
            "公開リファレンス",
            Some("https://example.org/ja".to_owned()),
            Some("strong-generic".to_owned()),
            "3",
            Vec::new(),
            "ja.md",
            "ja.json",
        );
        let cjk_id = cjk.id.clone();

        let mut shelf = KnowledgeShelf::new();
        shelf.upsert(spanish);
        shelf.upsert(arabic);
        shelf.upsert(cjk);

        let title_results = shelf.search("índice", |_| None);
        assert_eq!(
            title_results.first().map(|result| result.id.as_str()),
            Some(spanish_id.as_str())
        );

        let note_results = shelf.search("NAVEGACIÓN", |_| None);
        assert_eq!(
            note_results.first().map(|result| result.id.as_str()),
            Some(spanish_id.as_str())
        );

        let tag_results = shelf.search("MANUALES", |_| None);
        assert_eq!(
            tag_results.first().map(|result| result.id.as_str()),
            Some(spanish_id.as_str())
        );

        let arabic_results = shelf.search("المعرفة", |_| None);
        assert_eq!(
            arabic_results.first().map(|result| result.id.as_str()),
            Some(arabic_id.as_str())
        );

        let cjk_results = shelf.search("見出し", |record| {
            (record.id == cjk_id).then(|| "# 見出し\n知識ページ".to_owned())
        });
        assert_eq!(
            cjk_results.first().map(|result| result.id.as_str()),
            Some(cjk_id.as_str())
        );
    }

    #[test]
    fn shelf_search_uses_deterministic_tie_breaks() {
        let alpha = ShelfRecord::new("Alpha", None, None, "1", Vec::new(), "a.md", "a.json");
        let beta = ShelfRecord::new("Beta", None, None, "2", Vec::new(), "b.md", "b.json");
        let mut shelf = KnowledgeShelf::new();
        shelf.upsert(beta);
        shelf.upsert(alpha);

        let results = shelf.search("shared", |_| Some("shared".to_owned()));

        assert_eq!(
            results
                .iter()
                .map(|result| result.title.as_str())
                .collect::<Vec<_>>(),
            vec!["Alpha", "Beta"]
        );
    }

    #[test]
    fn session_serialization_roundtrips_history_bookmarks_origins_and_redirects()
    -> Result<(), Box<dyn std::error::Error>> {
        let requested = IndexUrl::parse("http://example.com/start")?;
        let redirect = IndexUrl::parse("https://example.com/start")?;
        let final_url = IndexUrl::parse("https://example.com/home")?;
        let docs = IndexUrl::parse("https://example.com/docs")?;
        let mut session = SessionState::new(SessionId::new("main"));
        session.ui.sidebar_mode = SessionSidebarMode::Regions;
        session.ui.reader_profile = ReaderProfile::Research;
        session.ui.reader_profile_manual = true;

        session.visit_entry(HistoryEntry::with_redirects(
            requested.clone(),
            final_url.clone(),
            vec![redirect.clone()],
        ));
        session.visit(docs.clone());
        assert!(session.go_back().is_some());
        session.bookmark_current("Home");
        session.bookmarks.update_details(
            &final_url,
            Some("Return later".to_owned()),
            vec!["home".to_owned(), "reference".to_owned()],
        );

        let restored = SessionState::deserialize(&session.serialize())?;

        assert_eq!(restored.id.as_str(), "main");
        assert_eq!(
            restored.history.current().map(|entry| &entry.final_url),
            Some(&final_url)
        );
        assert!(restored.bookmarks.contains(&final_url));
        let bookmark = restored
            .bookmarks
            .iter()
            .find(|bookmark| bookmark.url == final_url)
            .ok_or("missing bookmark")?;
        assert_eq!(bookmark.note.as_deref(), Some("Return later"));
        assert_eq!(
            bookmark.tags,
            vec!["home".to_owned(), "reference".to_owned()]
        );
        assert_eq!(
            restored
                .history
                .current()
                .and_then(|entry| entry.redirects.first()),
            Some(&redirect)
        );
        assert_eq!(
            restored
                .origins
                .get(&Origin::from_stored("https://example.com"))
                .map(|state| state.visits),
            Some(2)
        );
        assert_eq!(restored.ui.sidebar_mode, SessionSidebarMode::Regions);
        assert_eq!(restored.ui.reader_profile, ReaderProfile::Research);
        assert!(restored.ui.reader_profile_manual);
        Ok(())
    }

    #[test]
    fn session_sidebar_mode_names_are_stable() {
        let modes = [
            (SessionSidebarMode::Links, "links"),
            (SessionSidebarMode::Outline, "outline"),
            (SessionSidebarMode::Forms, "forms"),
            (SessionSidebarMode::Regions, "regions"),
            (SessionSidebarMode::Search, "search"),
            (SessionSidebarMode::Logs, "logs"),
        ];

        for (mode, name) in modes {
            assert_eq!(mode.as_str(), name);
            assert_eq!(mode.to_string(), name);
            assert_eq!(SessionSidebarMode::parse(name), Some(mode));
        }

        assert_eq!(
            SessionSidebarMode::Links.previous(),
            SessionSidebarMode::Logs
        );
        assert_eq!(SessionSidebarMode::Search.next(), SessionSidebarMode::Logs);
        assert_eq!(SessionSidebarMode::Logs.next(), SessionSidebarMode::Links);
        assert_eq!(SessionSidebarMode::parse("unknown"), None);
    }

    #[test]
    fn reader_profile_names_are_stable() {
        let profiles = [
            (ReaderProfile::Reader, "reader"),
            (ReaderProfile::Docs, "docs"),
            (ReaderProfile::Links, "links"),
            (ReaderProfile::Research, "research"),
            (ReaderProfile::Compact, "compact"),
            (ReaderProfile::Verbose, "verbose"),
        ];

        assert_eq!(ReaderProfile::all(), profiles.map(|(profile, _)| profile));

        for (profile, name) in profiles {
            assert_eq!(profile.as_str(), name);
            assert_eq!(profile.to_string(), name);
            assert_eq!(ReaderProfile::parse(name), Some(profile));
        }

        assert_eq!(ReaderProfile::parse("unknown"), None);
    }

    #[test]
    fn old_session_ui_lines_default_to_reader_profile() -> Result<(), Box<dyn std::error::Error>> {
        let restored =
            SessionState::deserialize("index-session-v1\nid\tmain\nui\tregions\nhistory\tnone")?;

        assert_eq!(restored.ui.sidebar_mode, SessionSidebarMode::Regions);
        assert_eq!(restored.ui.reader_profile, ReaderProfile::Reader);
        assert!(!restored.ui.reader_profile_manual);
        let restored = SessionState::deserialize(
            "index-session-v1\nid\tmain\nui\tregions\tdocs\tmanual\nhistory\tnone",
        )?;
        assert_eq!(restored.ui.reader_profile, ReaderProfile::Docs);
        assert!(restored.ui.reader_profile_manual);
        Ok(())
    }

    #[test]
    fn empty_session_roundtrips_and_current_bookmark_is_noop()
    -> Result<(), Box<dyn std::error::Error>> {
        let mut session = SessionState::new(SessionId::new("empty"));

        assert_eq!(session.bookmark_current("Nothing"), None);
        assert!(session.go_back().is_none());
        assert!(session.go_forward().is_none());

        let restored = SessionState::deserialize(&session.serialize())?;
        assert_eq!(restored.id.as_str(), "empty");
        assert!(restored.history.current().is_none());
        Ok(())
    }

    #[test]
    fn session_persists_to_disk() -> Result<(), Box<dyn std::error::Error>> {
        let path = temp_path("session");
        let mut session = SessionState::new(SessionId::new("disk"));
        let url = IndexUrl::parse("https://example.com/session")?;
        session.visit(url.clone());

        session.save_to_path(&path)?;
        let restored = SessionState::load_from_path(&path)?;
        std::fs::remove_file(&path)?;

        assert_eq!(
            restored.history.current().map(|entry| &entry.final_url),
            Some(&url)
        );
        Ok(())
    }

    #[test]
    fn bookmark_remove_returns_removed_entry() -> Result<(), Box<dyn std::error::Error>> {
        let url = IndexUrl::parse("https://example.com/remove")?;
        let mut store = BookmarkStore::new();
        store.add("Remove me", url.clone());

        let removed = store.remove(&url);

        assert_eq!(
            removed.map(|bookmark| bookmark.title),
            Some("Remove me".to_owned())
        );
        assert!(!store.contains(&url));
        Ok(())
    }

    #[test]
    fn bookmark_loader_rejects_invalid_records() {
        assert!(BookmarkStore::from_serialized("bad").is_err());
        assert!(BookmarkStore::from_serialized("index-bookmarks-v1\nonly-one-field").is_err());
        assert!(
            BookmarkStore::from_serialized("index-bookmarks-v1\nhttps://example.com\\\tTitle")
                .is_err()
        );
        assert!(BookmarkStore::from_serialized("index-bookmarks-v1\nbad-url\tTitle").is_err());
    }

    #[test]
    fn session_loader_rejects_invalid_records() {
        assert!(SessionState::deserialize("bad").is_err());
        assert!(SessionState::deserialize("index-session-v1\nhistory\t0").is_err());
        assert!(SessionState::deserialize("index-session-v1\nid\tmain\nbad\tfield").is_err());
        assert!(SessionState::deserialize("index-session-v1\nid\tmain\nhistory\t1").is_err());
        assert!(SessionState::deserialize("index-session-v1\nid\tmain\nhistory\tabc").is_err());
        assert!(
            SessionState::deserialize(
                "index-session-v1\nid\tmain\nhistory\tnone\nentry\tbad-url\thttps://example.com",
            )
            .is_err()
        );
        assert!(
            SessionState::deserialize(
                "index-session-v1\nid\tmain\nhistory\tnone\norigin\thttps://example.com\tabc\t",
            )
            .is_err()
        );
    }

    #[test]
    fn per_origin_state_records_visit_count_and_last_url() -> Result<(), Box<dyn std::error::Error>>
    {
        let first = IndexUrl::parse("https://example.com/one")?;
        let second = IndexUrl::parse("https://example.com/two")?;
        let mut state = OriginState::default();

        state.record_visit(first);
        state.record_visit(second.clone());

        assert_eq!(state.visits, 2);
        assert_eq!(state.last_url, Some(second));
        Ok(())
    }

    #[test]
    fn redirect_entries_keep_requested_final_and_hops() -> Result<(), Box<dyn std::error::Error>> {
        let requested = IndexUrl::parse("http://example.com")?;
        let hop = IndexUrl::parse("https://example.com")?;
        let final_url = IndexUrl::parse("https://www.example.com")?;
        let entry =
            HistoryEntry::with_redirects(requested.clone(), final_url.clone(), vec![hop.clone()]);

        assert_eq!(entry.requested_url, requested);
        assert_eq!(entry.final_url, final_url);
        assert_eq!(entry.redirects, vec![hop]);
        Ok(())
    }

    fn temp_path(name: &str) -> std::path::PathBuf {
        let mut path = std::env::temp_dir();
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .map_or(0, |duration| duration.as_nanos());
        path.push(format!("index-{name}-{nanos}.txt"));
        path
    }
}