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

export module Crafter.Review:Inventory;
import std;
import :Json;

// The partition of a frozen commit range — a `git format-patch` export — into
// review units for the coverage contract. It is MECHANICAL: no agent decides
// what the units are. Every non-blank line of the artifact belongs to
// exactly one unit, and the inventory fails when that does not hold. Fixed
// slots give what is NOT in the text a row of the coverage matrix too.
//
// Units (ids):
//   pK:subject   commit K's subject
//   pK:msg       commit K's message body (before the trailers), when not empty
//   pK:trailers  commit K's trailer block, when not empty
//   pK:diffstat  commit K's diffstat
//   pK:<file>#hdr  the diff header of <file> in commit K (mode, rename, blobs)
//   pK:<file>#H  hunk H of <file> in commit K; a hunk of a documentation file
//                that holds more than one heading-delimited part is cut into
//                #H.1, #H.2, ... (DocParts)
//   pK:outside   fixed slot: the in-repository users and callers of what
//                commit K changes, outside its diff
//   pK:absent    fixed slot: what a reviewer expects in commit K and does not
//                find
//   whole:*      fixed slots (WholeCommits)
export namespace Crafter::Review::Inventory {
    struct WholeSlot {
        std::string_view id;
        std::string_view description;
    };
    constexpr std::array<WholeSlot, 3> WholeCommits = {{
        {"whole:order", "commit ordering and bisectability — each commit a self-contained step that leaves the repository consistent (no later commit in the range repairs an earlier one, nothing is used before the commit that adds it), the declared base"},
        {"whole:absent", "what a reviewer of this repository expects the range to contain and it does not — a test, a version/changelog bump, a doc or packaging update, a migration for existing installs, a message for a body-less commit"},
        {"whole:behaviour", "the user-visible behaviour of the range, exercised end to end in the running application — every behaviour the code and the messages promise, as a user sees it; the flows the range touches and the adjacent flows that share what it changes; what a user expects the range to deliver and does not get"},
    }};

    // [a, b) is one hunk of a Markdown file, lines[a] its @@ line: its
    // partition at the headings on the new side of the diff, outside fenced
    // code blocks, once the part before holds anything but headings.
    std::vector<std::pair<std::size_t, std::size_t>> DocParts(std::span<const std::string> lines, std::size_t a, std::size_t b);
    // The first non-blank line, stripped and cut to 90 code points.
    std::string Excerpt(std::span<const std::string> lines);

    struct Series {
        // Every patch's lines, one after the other: what unit lines number.
        std::vector<std::string> lines;
        // Units ({id, lines, excerpt}), the whole slots not yet among them.
        Json units;
    };
    Series PartitionSeries(const std::filesystem::path& dir, bool splitDocs = true);

    // A partition that broke the invariant.
    class InvariantError : public std::runtime_error {
    public:
        using std::runtime_error::runtime_error;
    };

    struct Built {
        // What `inventory commits <dir>` prints: {mode, artifact, hash8,
        // units, invariant, count}.
        Json out;
        std::vector<std::string> lines;
    };
    // `artifact` is kept as it is spelled: the inventory records it so.
    Built Build(std::string_view mode, std::string_view artifact);

    // `crafter-review inventory commits <dir>`: the partition as indented
    // JSON on stdout. Exit 1 on a broken invariant or a bad command line.
    std::int32_t Main(std::span<const std::string_view> args);
}