// SPDX-License-Identifier: LGPL-3.0-only
// SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®

export module Crafter.Build:Agents;
import std;
namespace fs = std::filesystem;

// Dependency notes. A crafter-build project ships an AGENTS.consumer.md beside
// its project.cpp, written for the agents of the projects that depend on it,
// and crafter-build keeps those files in each consumer's AGENTS.md. Without
// that, an agent working on a consumer knows nothing about the libraries it
// builds against unless someone copied the knowledge in by hand, and a copy
// goes stale the moment the library changes.
export namespace Crafter {
    struct Configuration;

    // Which dependencies' notes a project's AGENTS.md carries: the value of
    // Configuration::dependencyNotes.
    enum class DependencyNotes {
        // The projects this one builds against, and the projects those build
        // against, all the way down.
        Transitive,
        // Only the projects this one's own configurations, tests and
        // `#pragma crafter dependency` lines name.
        Direct,
        // None. A section an earlier build wrote is removed.
        None,
    };

    // One dependency's AGENTS.consumer.md, ready to merge.
    struct DependencyNote {
        // Where it came from, written into the comment above it: the git URL,
        // or for a local project the file's path relative to the consumer.
        std::string source;
        // The file's content, without leading blank lines or trailing
        // whitespace.
        std::string text;
    };

    // `agentsMd` with its dependency notes section holding `notes`, in order.
    // A file without a section gets one appended after a blank line; one
    // with a section has it rewritten in place, wherever it was moved to;
    // and empty `notes` remove it together with that blank line, so a file
    // that only ever gained the section gets its own bytes back.
    //
    // The two marker lines count only as whole lines outside fenced code
    // blocks, which is what lets a document quote them. Throws, naming the
    // line, when the markers are unbalanced or the document ends inside a
    // code block: guessing which part of someone's file is generated would
    // overwrite their text, and missing the section would add a second one
    // on every build. Also throws for a note that would break the section
    // when it is read back: one with a marker line of its own, or a code
    // block it never closes.
    std::string MergeDependencyNotes(std::string_view agentsMd, std::span<const DependencyNote> notes);

    // Refresh the dependency notes section of the AGENTS.md beside
    // `projectFile` from the AGENTS.consumer.md of every dependency
    // project.dependencyNotes selects. `project` is the Configuration that
    // file returned, after LoadProject: loading is what found the
    // dependencies. Does nothing when there is no AGENTS.md, which is never
    // created. Writes only when the text changes, and returns whether it
    // did. An unreadable file, a failed write, malformed markers and a
    // dependency's unusable notes are warnings: the notes never fail a build.
    bool UpdateAgentsMd(const Configuration& project, const fs::path& projectFile);
}