bynk_lsp/

hover.rs

//! #611 (ADR 0190): hover's resolution ladder, as one pure function.
//!
//! `Backend::hover` is transport — it resolves the cursor position, gathers the
//! round's tables and the live buffer, and packages the result as an LSP
//! `Hover`. The *order* the rungs are tried in is the behaviour: #611's gap B was
//! a fall-through bug, where a rung that resolved the offset correctly but
//! rendered nothing let a later, name-matching rung answer instead — a
//! confidently wrong hover. That order lives here, once, so a test can **pin** it
//! rather than replicate it (a replica agrees with the original only until
//! someone reorders one of them).
//!
//! Two text sources, deliberately: the index rungs read the round's **analysed
//! snapshot** (the tables' spans index into it), while the lexical rungs read the
//! **live buffer**, which is what makes hover work mid-edit. They diverge while
//! the user types, so the ladder keeps them distinct rather than assuming one.
//!
//! The rungs, in trial order (see [`hover_content`]'s inline numbering):
//! 1. the binding index — a resolved symbol reference, described from its
//!    defining file (a resolved `Service` gets a #855 wire-contract appendix);
//! 2. a `store` field operation;
//! 3. a local/param/`self`;
//! 4. #855: a handler's HEADER (`on`, the method/kind token, the route
//!    literal) — guarded to that byte range so it cannot shadow rung 1;
//! 5. a top-level declaration by name (lexical, first live-buffer rung);
//! 6. the `key`/`store` contextual keywords and agent-state references;
//! 7. a handler-position `@cache` annotation;
//! 8. a `Recv.member` name-receiver access;
//! 9. a project-wide name scan;
//! 10. the embedded first-party sources.

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

use bynk_check::checker::Types;
use bynk_check::index::SymbolKind;
use bynk_syntax::span::Span;
use tower_lsp::lsp_types::Url;

/// The analysed round's tables, positioned at the cursor.
pub struct HoverAnalysis<'a> {
    pub index: &'a bynk_check::index::ProjectIndex,
    /// Project-relative path → the analysed text.
    pub snapshots: &'a HashMap<PathBuf, String>,
    pub locals: &'a bynk_check::locals::FileLocals,
    pub expr_types: &'a bynk_check::expr_types::FileExprTypes,
    /// T3.6b (R4.1): the table `expr_types`' `TyId`s resolve against.
    pub tys: &'a Types,
    /// The cursor's file (project-relative) and its offset **into the snapshot**.
    pub rel: &'a Path,
    pub offset: usize,
    /// #848: the round's project root — resolves a doc-link's `SiteRef` into
    /// a `file://` hover-Markdown target.
    pub project_root: &'a Path,
    /// #848: qualified unit name → its doc-comment intra-doc-link search
    /// order, for rung 1's doc-link rewrite.
    pub doc_scope: &'a HashMap<String, Vec<String>>,
    /// #855: qualified context/adapter unit name → the combined type table
    /// and service/agent tables the wire-contract peek needs.
    pub boundary_info: &'a HashMap<String, bynk_ide::ContextBoundaryInfo>,
    /// #855: how many **real** contexts/adapters this project has — computed
    /// once per round by the transport with
    /// `bynk_ide::wire_contract::real_context_count`, never re-derived here
    /// as a bare `boundary_info.len()` (see that function's doc: the
    /// synthetic toolchain `bynk` capability unit would otherwise count as a
    /// second "context" and `NoCrossContextReason::SingleContext` would
    /// almost never fire).
    pub context_count: usize,
}

/// Everything the ladder reads.
pub struct HoverInput<'a> {
    /// The analysed round; `None` when the file is outside it — the lexical
    /// rungs still answer from the live buffer.
    pub analysis: Option<HoverAnalysis<'a>>,
    /// The **live** buffer and the cursor's offset into it; `None` when the
    /// document is not open — the index rungs still answer from the snapshot.
    pub doc: Option<(&'a str, usize)>,
    pub uri: &'a Url,
    /// Content-ownership track (#1086): a pre-read `(path, content)` map for
    /// the project's `.bynk` files (the caller's overlay-then-disk sweep) —
    /// was a bare path list the resolution rungs below read from disk
    /// themselves. Every rung that reads project files (8's `resolve_label`,
    /// 9's `describe_symbol_cross_file`) takes this map directly now.
    pub files: Option<&'a HashMap<PathBuf, String>>,
}

/// The hover Markdown for the cursor, or `None` when no rung resolves it.
///
/// The rung order is the contract; see the module doc. Each rung is tried in
/// turn and the first `Some` wins.
pub fn hover_content(input: &HoverInput<'_>) -> Option<String> {
    if let Some(a) = &input.analysis {
        let tys = a.tys;
        // 1. v0.25: binding-index path — a resolved symbol reference, described
        //    from its *defining* file (names are unique per file, so the per-file
        //    lookup is exact). Binding-correct: a duplicate name in another unit
        //    describes the bound declaration, not the first name match.
        //
        //    v0.166 (ADR 0191): every `SymbolKind` now has a renderer arm, so a
        //    resolved key is answered here rather than falling through to a name
        //    match below. The `Some` guard remains — it is what a new kind added
        //    without an arm would fall through, silently, which is how
        //    `Method`/`CapabilityOp` came to render the wrong declaration.
        if let Some((key, def)) = crate::index_queries::definition_at(a.index, a.rel, a.offset)
            && let Some(def_text) = a.snapshots.get(&def.path)
            && let Some(content) = crate::symbols::describe_symbol(def_text, &key.name)
        {
            // #848: rewrite any resolvable intra-doc link in the rendered
            // doc comment into a Markdown link, scoped to `key.unit` (the
            // declaring unit doc-link resolution searches from).
            let content = crate::symbols::linkify_doc_links(
                &content,
                a.index,
                a.doc_scope,
                a.project_root,
                &key.unit,
            );
            // #855: a resolved `Service` symbol (the declaration's own name,
            // or a cross-context/test-service call site — both record this
            // kind, see `bynk-emit/src/project/symbols.rs`) gets its wire
            // contract appended after everything `describe_symbol` already
            // rendered. This changes only the *tail* of what rung 1 already
            // returns `Some` for — never whether it answers.
            let content = if key.kind == SymbolKind::Service {
                match wire_contract_for_service_key(a, key, &def.path, def_text) {
                    Some(model) => format!("{content}{}", wire_contract_appendix(&model)),
                    None => content,
                }
            } else {
                content
            };
            return Some(content);
        }
        // 2. #611 (gap C): a `store` field's operation (`items.put(…)`) — a
        //    structural match on the enclosing agent's declared field, so it
        //    outranks the locals rung below, which guesses by name in scope.
        //    Takes `locals` to honour the checker's by-provenance dispatch: a
        //    local shadowing the field makes this an ordinary value method.
        if let Some(text) = a.snapshots.get(a.rel)
            && let Some(content) = crate::symbols::describe_store_op_at(
                text,
                a.offset,
                a.locals.get(a.rel).map_or(&[], |l| l.as_slice()),
            )
        {
            return Some(content);
        }
        // 3. v0.122 (slice 1): a local / parameter → its inferred type, and
        //    `self` → its receiver/agent type. Both read the retained analysis
        //    tables and run before the lexical fallback, which knows only
        //    declarations by name.
        if let Some(text) = a.snapshots.get(a.rel) {
            let local = a
                .locals
                .get(a.rel)
                .and_then(|locals| crate::locals_nav::describe_local_at(locals, text, a.offset))
                .or_else(|| {
                    let entries = a.expr_types.get(a.rel)?;
                    crate::symbols::describe_self_at(text, a.offset, entries, tys)
                });
            if let Some(content) = local {
                return Some(content);
            }
        }
        // 4. #855: the handler HEADER — the `on` keyword, the HTTP method /
        //    handler-kind token, and any route string literal. No earlier rung
        //    (nor any later lexical one) ever answers here today: `GET` lexes
        //    as a bare `Ident` with no index symbol, and no top-level
        //    declaration is named after it. Guarded to the header's own byte
        //    range — from the handler's span start up to (but excluding) its
        //    first param's span start, or its body's span start with no
        //    params — which contains only tokens that are never an index
        //    symbol, so this rung is provably unable to shadow rung 1's
        //    resolution of, say, a param's *type* name (`client: ClientId`),
        //    which always sits past that boundary. See `header_handler_at`.
        if let Some(text) = a.snapshots.get(a.rel)
            && let Some((service_name, handler)) = header_handler_at(text, a.offset)
            && let Some((unit, _)) = bynk_ide::symbols::own_declaration_name(text)
            && let Some(info) = a.boundary_info.get(&unit)
        {
            let expr_types = a.expr_types.get(a.rel).map(|v| v.as_slice()).unwrap_or(&[]);
            if let Some(model) = bynk_ide::wire_contract::wire_contract_for_service(
                &unit,
                text,
                &service_name,
                &handler,
                info,
                expr_types,
                tys,
                a.context_count,
            ) {
                return Some(wire_contract_standalone(&model));
            }
        }
    }

    // The remaining rungs are lexical, over the **live** buffer.
    let (text, offset) = input.doc?;
    let Some((name, span)) = identifier_at(text, offset) else {
        // v0.121 (ADR 0156): the mechanical coverage test requires every
        // lowercase-initial keyword to have *a* hover path. A bare keyword token
        // (`requires`, `suite`, …) never resolves as an identifier above, so it
        // falls here — its one-line `keywords` registry doc, the same text
        // completion shows. Richer per-declaration hover is `describe_symbol`'s
        // job, not this fallback's.
        return crate::symbols::describe_keyword_at(text, offset).map(str::to_string);
    };
    // 5. A top-level declaration in this file (fast path).
    if let Some(content) = crate::symbols::describe_symbol(text, &name) {
        return Some(content);
    }
    // 6. v0.137.0 (ADR 0161) + #611 (gap A): the `key`/`store` contextual
    //    keywords, the agent state fields they declare, and — since #611 — a
    //    *reference* to one from the agent's body. Single-file-local, so it
    //    resolves before any project-wide scan.
    if let Some(content) = crate::symbols::describe_agent_state_at(text, span.start) {
        return Some(content);
    }
    // 7. v0.140 (ADR 0163): a handler-position `@cache` annotation — not a symbol
    //    and no local, so it resolves here beside the agent state.
    if let Some(content) = crate::symbols::describe_handler_annotation_at(text, span.start) {
        return Some(content);
    }
    // 8. v0.123 (slice 2, DECISION B): a `Recv.member` name-receiver access — a
    //    capability op (`Clock.now`), a refined/opaque `of`/`unsafe`, or a type
    //    static — via the same path signature help uses, over the project and the
    //    embedded surface. Before the cross-file / first-party name scans.
    crate::symbols::qualified_callee_at(text, span)
        .and_then(|callee| crate::signature_help::resolve_label(&callee, text, input.files))
        .map(|sig| format!("```bynk\n{sig}\n```"))
        // 9. A project-wide scan (v1.1), then 10. the embedded first-party
        //    sources (slice 9) — so `uses`/`consumes` names resolve across
        //    file boundaries (§3.4) and stdlib/surface symbols surface too.
        //    Content-ownership track (#1086) slice 1: `describe_symbol_cross_file`
        //    now takes `input.files`'s content map directly — no more deriving
        //    a path list to hand it.
        .or_else(|| {
            input
                .files
                .and_then(|content| {
                    crate::symbols::describe_symbol_cross_file(content, input.uri, &name)
                })
                .map(|(_other_uri, desc)| desc)
        })
        .or_else(|| crate::symbols::describe_firstparty_symbol(&name))
}

/// The identifier-ish token covering `offset` — its text and span.
///
/// Hole-aware (issue #473): interpolation holes are expanded, so a cursor inside
/// `"… \(name) …"` lands on the hole's identifier token rather than the opaque
/// `InterpStr` token. The token-kind filter is wider than `Ident` because the
/// literal kinds carry hover-worthy names too (`Result`, `Option`, `Effect`).
fn identifier_at(text: &str, offset: usize) -> Option<(String, Span)> {
    use bynk_syntax::lexer::TokenKind;
    let tokens = bynk_syntax::lexer::tokenize_expanding_holes(text).ok()?;
    tokens
        .iter()
        .find(|t| {
            t.span.start <= offset
                && offset < t.span.end
                && matches!(
                    t.kind,
                    TokenKind::Ident
                        | TokenKind::Int
                        | TokenKind::String
                        | TokenKind::Bool
                        | TokenKind::Float
                        | TokenKind::Result
                        | TokenKind::Option
                        | TokenKind::Effect
                )
        })
        .map(|t| (text[t.span.start..t.span.end].to_string(), t.span))
}

// ---------------------------------------------------------------------
// #855: wire-contract rendering — rung 1's appendix and rung 4's standalone
// content share the same body renderer ([`wire_contract_body`]); they differ
// only in what comes before it (an existing `describe_symbol` block, versus
// nothing).
// ---------------------------------------------------------------------

/// Resolve a resolved-`Service`-symbol's wire contract, for rung 1's
/// appendix. A service may declare more than one handler (several HTTP
/// routes on one service, say); this module has no way to tell *which* one
/// the author meant by hovering the service's bare name (a declaration site,
/// or a cross-context/test-service call site — neither carries a handler
/// selector). Rather than guess, this answers only the unambiguous case: a
/// service with **exactly one** handler. That covers every worked example in
/// the issue (a single-route HTTP service, a single-handler `on call`
/// service) and every #855 fixture; a multi-handler service simply gets no
/// appendix, which is rung 1's pre-#855 behaviour unchanged — never a wrong
/// answer, only sometimes an absent one.
fn wire_contract_for_service_key(
    a: &HoverAnalysis<'_>,
    key: &bynk_check::index::SymbolKey,
    def_path: &Path,
    def_text: &str,
) -> Option<bynk_ide::wire_contract::WireContractModel> {
    let tys = a.tys;
    let info = a.boundary_info.get(&key.unit)?;
    let svc = info.services.get(&key.name)?;
    let [handler] = svc.handlers.as_slice() else {
        return None;
    };
    let expr_types = a
        .expr_types
        .get(def_path)
        .map(|v| v.as_slice())
        .unwrap_or(&[]);
    bynk_ide::wire_contract::wire_contract_for_service(
        &key.unit,
        def_text,
        &key.name,
        handler,
        info,
        expr_types,
        tys,
        a.context_count,
    )
}

/// Locate the `Handler` (and its owning service's name) whose **header**
/// contains `offset` — the `on` keyword, the handler-kind/HTTP-method token,
/// and any route string literal, but *none* of its params or body. Mirrors
/// `bynk_ide::wire_contract::wire_contract_at`'s re-parse-and-find-the-
/// enclosing-handler convention; duplicated (rather than reused) because the
/// guard below needs the raw `Handler`'s param/body spans, which
/// `wire_contract_at`'s return value (a `WireContractModel`, not an AST node)
/// does not carry.
fn header_handler_at(text: &str, offset: usize) -> Option<(String, bynk_syntax::ast::Handler)> {
    use bynk_syntax::ast::{CommonsItem, SourceUnit};
    let tokens = bynk_syntax::lexer::tokenize(text).ok()?;
    let (parsed, _errs) = bynk_syntax::parser::parse_unit_with_recovery(&tokens, text);
    let items: &[CommonsItem] = match parsed.as_ref()? {
        SourceUnit::Context(c) => &c.items,
        SourceUnit::Adapter(a) => &a.items,
        SourceUnit::Commons(_) | SourceUnit::Suite(_) => return None,
    };
    for item in items {
        let CommonsItem::Service(s) = item else {
            continue;
        };
        for h in &s.handlers {
            // The safety property: this range holds only `on`, the
            // kind/method token, and the route literal — never a param name,
            // a type name, or anything else an earlier rung (or a later
            // lexical one) could already resolve. See the module doc and
            // rung 4's own comment.
            let prefix_end = h
                .params
                .first()
                .map(|p| p.span.start)
                .unwrap_or(h.body.span.start);
            if h.span.start <= offset && offset < prefix_end {
                return Some((s.name.name.clone(), h.clone()));
            }
        }
    }
    None
}

/// The Markdown facts shared by rung 1's appendix and rung 4's standalone
/// render: the request envelope (all three cases), the cross-context
/// contract form + hash (`on call` only), and — HTTP handlers only — the
/// reachable response status set.
fn wire_contract_body(model: &bynk_ide::wire_contract::WireContractModel) -> String {
    use bynk_ide::wire_contract::{BoundaryKind, Envelope};

    let mut out = String::new();
    if let BoundaryKind::Http { method, path } = &model.kind {
        out.push_str(&format!("`{} {}`\n\n", method.as_str(), path));
    }

    out.push_str("**Request:** ");
    match &model.envelope {
        Envelope::Empty => out.push_str("no body — the handler never reads it.\n\n"),
        Envelope::Bare { param, .. } => out.push_str(&format!(
            "the request body **is** the value of `{param}` — not wrapped in an object.\n\n"
        )),
        Envelope::Keyed { params } => {
            let names: Vec<&str> = params.iter().map(|(n, _)| n.as_str()).collect();
            out.push_str(&format!(
                "an object keyed by `{}`, in declaration order.\n\n",
                names.join("`, `")
            ));
        }
    }

    if let Some(contract) = &model.contract {
        out.push_str(&format!(
            "**Cross-context contract** (hash `{}`) — change any of this and \
             already-deployed callers get a 409:\n\n```\n{}\n```\n\n",
            contract.hash, contract.normal_form
        ));
    }

    if !model.responses.is_empty() {
        out.push_str("**Responses:**\n\n");
        for r in &model.responses {
            out.push_str(&format!("- `{} {}`\n", r.status, r.variant));
        }
        out.push('\n');
    }

    out
}

/// Rung 1's wire-contract appendix — separated from whatever
/// `describe_symbol` already rendered by a rule, so it reads as a distinct
/// section rather than a continuation of the declaration's own doc comment.
fn wire_contract_appendix(model: &bynk_ide::wire_contract::WireContractModel) -> String {
    format!(
        "\n\n---\n\n**Wire contract**\n\n{}",
        wire_contract_body(model)
    )
}

/// Rung 4's standalone render — hovering the header *is* the question, so
/// this is the whole answer, headed by the service/handler name rather than
/// appended after one.
fn wire_contract_standalone(model: &bynk_ide::wire_contract::WireContractModel) -> String {
    format!(
        "**Wire contract** — `{}`\n\n{}",
        model.service,
        wire_contract_body(model)
    )
}