tldr-cli 0.4.0

//! Context command - Build LLM context
//!
//! Generates token-efficient LLM context from an entry point.
//! Auto-routes through daemon when available for ~35x speedup.

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

use anyhow::Result;
use clap::Args;

use tldr_core::types::RelevantContext;
use tldr_core::{get_relevant_context, Language};

use crate::commands::daemon_router::{params_with_entry_depth, try_daemon_route};
use crate::output::{OutputFormat, OutputWriter};

/// Build LLM-ready context from entry point
#[derive(Debug, Args)]
pub struct ContextArgs {
    /// Entry point function name
    pub entry: String,

    /// Project root directory as positional argument (mirrors sibling
    /// path-taking commands like `impact`, `whatbreaks`). When set, this
    /// takes precedence over `--project`. (med-cleanup-bundle-v1 / M1)
    #[arg(default_value = ".")]
    pub path: PathBuf,

    /// Project root directory (deprecated alias for the positional path
    /// argument; kept for back-compat). (med-cleanup-bundle-v1 / M1)
    #[arg(long, short = 'p')]
    pub project: Option<PathBuf>,

    /// Programming language
    #[arg(long, short = 'l')]
    pub lang: Option<Language>,

    /// Maximum traversal depth
    #[arg(long, short = 'd', default_value = "3")]
    pub depth: usize,

    /// Include function docstrings
    #[arg(long)]
    pub include_docstrings: bool,

    /// Filter to functions in this file (for disambiguating common names like "render")
    #[arg(long)]
    pub file: Option<PathBuf>,
}

impl ContextArgs {
    /// Resolve the effective project path. The positional `path` argument
    /// is the canonical input; `--project` is kept as a back-compat alias
    /// and only wins when the positional path is left at its default ".".
    /// (med-cleanup-bundle-v1 / M1)
    fn effective_project(&self) -> PathBuf {
        match &self.project {
            Some(p) if self.path == PathBuf::from(".") => p.clone(),
            _ => self.path.clone(),
        }
    }

    /// Run the context command
    pub fn run(&self, format: OutputFormat, quiet: bool) -> Result<()> {
        let writer = OutputWriter::new(format, quiet);

        let mut project_path = self.effective_project();

        // language-adapter-fixes-v1 (P13.AGG13-5) /
        // context-file-func-cross-lang-and-cpp-qualified-v1 (P14.AGG13-5,
        // AGG14-8): accept the `<file>:<func>` shorthand so users can
        // disambiguate common function names without typing `--file`
        // separately. The shape mirrors `tldr explain <file> <func>` and
        // `tldr resources <file> <func>`.
        //
        // We walk colons RIGHT-TO-LEFT and pick the leftmost split whose
        // file_part exists on disk. The legacy single-rfind form failed
        // for C++ qualified names because
        // `path/x.cpp:XMLDocument::Parse`'s last `:` lands inside `::`,
        // leaving file_part = `path/x.cpp:XMLDocument:` which is not a
        // file. Walking colons backward fixes this: the second-to-last
        // colon yields file_part = `path/x.cpp` (valid file) and
        // func_part = `XMLDocument::Parse` — the form the per-function
        // lookup now accepts (P14.AGG14-3 in `find_function_node`).
        // Windows drive letters (`C:\foo\bar.js:foo`) keep working
        // because the leftmost split where `C:\foo\bar.js` is a file
        // wins (the earlier `C:` split returns a non-file).
        let (entry, derived_file): (String, Option<PathBuf>) =
            match split_file_func_shorthand(&self.entry) {
                Some((file, func)) => (func, Some(file)),
                None => (self.entry.clone(), None),
            };

        // The user-supplied --file (if any) wins over the derived form so
        // explicit flags always take precedence over inferred shorthands.
        let effective_file: Option<PathBuf> =
            self.file.clone().or_else(|| derived_file.clone());

        // Auto-derive project root from file when shorthand was used and
        // the user didn't supply an explicit one. Honour `.git` /
        // `package.json` / `Cargo.toml` markers; otherwise fall back to
        // the file's immediate parent directory. This keeps the
        // shorthand useful from any cwd.
        if derived_file.is_some()
            && self.path == PathBuf::from(".")
            && self.project.is_none()
        {
            if let Some(file) = effective_file.as_ref() {
                if let Some(root) = infer_project_root_from_file(file) {
                    project_path = root;
                }
            }
        }

        // Determine language (auto-detect from directory, default to Python)
        let language = self
            .lang
            .unwrap_or_else(|| Language::from_directory(&project_path).unwrap_or(Language::Python));

        // Try daemon first for cached result. Only route through the
        // daemon when there is no derived-file disambiguation, since the
        // daemon protocol does not currently propagate the `--file`
        // filter (would silently ignore the disambiguator).
        if effective_file.is_none() {
            if let Some(context) = try_daemon_route::<RelevantContext>(
                &project_path,
                "context",
                params_with_entry_depth(&entry, Some(self.depth)),
            ) {
                // Output based on format
                if writer.is_text() {
                    // Use the built-in LLM string format
                    let text = context.to_llm_string();
                    writer.write_text(&text)?;
                    return Ok(());
                } else {
                    writer.write(&context)?;
                    return Ok(());
                }
            }
        }

        // Fallback to direct compute
        writer.progress(&format!(
            "Building context for {} (depth={})...",
            entry, self.depth
        ));

        // Get relevant context
        let context = get_relevant_context(
            &project_path,
            &entry,
            self.depth,
            language,
            self.include_docstrings,
            effective_file.as_deref(),
        )?;

        // Output based on format
        if writer.is_text() {
            // Use the built-in LLM string format
            let text = context.to_llm_string();
            writer.write_text(&text)?;
        } else {
            writer.write(&context)?;
        }

        Ok(())
    }
}

/// Parse the `<file>:<func>` shorthand argument into a `(file_path,
/// func_name)` pair, walking colons right-to-left to find the leftmost
/// split point whose file_part exists on disk.
///
/// context-file-func-cross-lang-and-cpp-qualified-v1
/// (P14.AGG13-5 / AGG14-3): the legacy `rfind(':')` form failed for
/// names that themselves contain `:` (notably C++ `Class::method`).
/// For input `path/x.cpp:XMLDocument::Parse` we now try the rightmost
/// colon first (file_part = `path/x.cpp:XMLDocument:`, not a file →
/// reject), then the next colon (file_part = `path/x.cpp`, valid →
/// accept) and emit func_part = `XMLDocument::Parse`. This keeps
/// Windows drive-letter paths working (`C:\foo\bar.js:foo` returns the
/// `C:\foo\bar.js` split because the earlier `C:` split is not a file).
///
/// Returns `None` when no split is valid; callers fall back to the
/// bare-name interpretation for genuine names containing `:` like
/// `Module::Sub::fn` invoked without a file prefix.
fn split_file_func_shorthand(entry: &str) -> Option<(PathBuf, String)> {
    let mut idx = entry.rfind(':')?;
    loop {
        if idx == 0 || idx + 1 >= entry.len() {
            // Search further-left colons (idx==0 means leading ':').
            match entry[..idx].rfind(':') {
                Some(prev) => {
                    idx = prev;
                    continue;
                }
                None => return None,
            }
        }
        let file_part = &entry[..idx];
        let func_part = &entry[idx + 1..];
        // func_part starts with `:` => we landed inside a `::` group;
        // the next iteration will move further left, but the candidate
        // file_part is also invalid as a file in that case (ends with
        // `:`), so a single `is_file()` check correctly rejects it.
        let candidate = PathBuf::from(file_part);
        if candidate.is_file() && !func_part.is_empty() && !func_part.starts_with(':') {
            return Some((candidate, func_part.to_string()));
        }
        match entry[..idx].rfind(':') {
            Some(prev) => idx = prev,
            None => return None,
        }
    }
}

/// Walk upward from `file`'s parent directory until we hit a directory
/// containing one of the common project-root markers (`.git`,
/// `package.json`, `Cargo.toml`, `go.mod`, `pyproject.toml`,
/// `pom.xml`, `build.gradle*`, `*.csproj`, `mix.exs`, `dune-project`).
/// Returns `Some(parent_dir)` as a fallback if no marker is found.
///
/// language-adapter-fixes-v1 (P13.AGG13-5): used by the context command
/// when the user invokes the `<file>:<func>` shorthand without an
/// explicit project path. Lets `tldr context /path/to/repo/src/x.js:foo`
/// resolve from any cwd, mirroring `cd /path/to/repo && tldr context foo`.
fn infer_project_root_from_file(file: &Path) -> Option<PathBuf> {
    let abs = file.canonicalize().unwrap_or_else(|_| file.to_path_buf());
    let parent = abs.parent()?;
    const MARKERS: &[&str] = &[
        ".git",
        "package.json",
        "Cargo.toml",
        "go.mod",
        "pyproject.toml",
        "pom.xml",
        "build.gradle",
        "build.gradle.kts",
        "mix.exs",
        "dune-project",
        "Package.swift",
    ];
    let mut cursor: Option<&Path> = Some(parent);
    while let Some(dir) = cursor {
        for m in MARKERS {
            if dir.join(m).exists() {
                return Some(dir.to_path_buf());
            }
        }
        // Also accept any *.csproj sibling (C# projects).
        if let Ok(entries) = std::fs::read_dir(dir) {
            for entry in entries.flatten() {
                if entry
                    .path()
                    .extension()
                    .and_then(|e| e.to_str())
                    .map(|e| e == "csproj" || e == "sln")
                    .unwrap_or(false)
                {
                    return Some(dir.to_path_buf());
                }
            }
        }
        cursor = dir.parent();
    }
    Some(parent.to_path_buf())
}