move git out of contributions

src/commands/contributions.zig

@@ -21,6 +21,7 @@
 const std = @import("std");
 const zfin = @import("../root.zig");
 const cli = @import("common.zig");
+const git = @import("../git.zig");
 const fmt = cli.fmt;
 const Date = zfin.Date;
 const Lot = zfin.Lot;
@@ -44,7 +45,7 @@ pub fn run(
     const arena = arena_state.allocator();
 
     // 1. Figure out the git repo and the portfolio's path inside it.
-    const repo = findGitRepo(arena, portfolio_path) catch |err| {
+    const repo = git.findRepo(arena, portfolio_path) catch |err| {
         switch (err) {
             error.NotInGitRepo => try cli.stderrPrint("Error: contributions requires portfolio.srf to be in a git repo.\n"),
             error.GitUnavailable => try cli.stderrPrint("Error: could not run 'git'. Is git installed and on PATH?\n"),
@@ -54,7 +55,7 @@ pub fn run(
     };
 
     // 2. Decide which snapshots to compare.
-    const status = try pathStatus(arena, repo.root, repo.rel_path);
+    const status = try git.pathStatus(arena, repo.root, repo.rel_path);
     if (status == .untracked) {
         try cli.stderrPrint("Error: portfolio.srf is not tracked in git. Add and commit it first.\n");
         return;
@@ -63,7 +64,7 @@ pub fn run(
 
     // 3. Pull both snapshots.
     const before = if (dirty)
-        gitShow(arena, repo.root, "HEAD", repo.rel_path) catch |err| {
+        git.show(arena, repo.root, "HEAD", repo.rel_path) catch |err| {
             switch (err) {
                 error.PathMissingInRev => try cli.stderrPrint("Error: portfolio.srf not present at HEAD.\n"),
                 else => try cli.stderrPrint("Error reading HEAD:portfolio.srf from git.\n"),
@@ -71,7 +72,7 @@ pub fn run(
             return;
         }
     else
-        gitShow(arena, repo.root, "HEAD~1", repo.rel_path) catch |err| {
+        git.show(arena, repo.root, "HEAD~1", repo.rel_path) catch |err| {
             switch (err) {
                 error.PathMissingInRev => try cli.stderrPrint("Error: portfolio.srf not present at HEAD~1.\n"),
                 error.UnknownRevision => try cli.stderrPrint("Error: no prior commit to compare against (HEAD~1 does not exist).\n"),
@@ -86,7 +87,7 @@ pub fn run(
             return;
         }
     else
-        gitShow(arena, repo.root, "HEAD", repo.rel_path) catch {
+        git.show(arena, repo.root, "HEAD", repo.rel_path) catch {
             try cli.stderrPrint("Error reading HEAD:portfolio.srf from git.\n");
             return;
         };
@@ -141,108 +142,10 @@ pub fn run(
 }
 
 // ── Git discovery / invocation ───────────────────────────────
-
+//
-const RepoInfo = struct {
+// Git plumbing lives in `src/git.zig` (shared with future snapshot
-    /// Absolute path to the repo root.
+// features). This module only classifies which revisions to diff and
-    root: []const u8,
+// how to interpret the result.
-    /// Relative path from root to the portfolio file (using '/'-style separators).
-    rel_path: []const u8,
-};
-
-fn findGitRepo(allocator: std.mem.Allocator, portfolio_path: []const u8) !RepoInfo {
-    // Resolve the portfolio file's directory.
-    const abs_path = try std.fs.cwd().realpathAlloc(allocator, portfolio_path);
-    const dir = std.fs.path.dirname(abs_path) orelse "/";
-
-    // git -C <dir> rev-parse --show-toplevel
-    const result = std.process.Child.run(.{
-        .allocator = allocator,
-        .argv = &.{ "git", "-C", dir, "rev-parse", "--show-toplevel" },
-        .max_output_bytes = 64 * 1024,
-    }) catch {
-        return error.GitUnavailable;
-    };
-
-    switch (result.term) {
-        .Exited => |code| if (code != 0) return error.NotInGitRepo,
-        else => return error.NotInGitRepo,
-    }
-
-    const root_raw = std.mem.trim(u8, result.stdout, " \t\r\n");
-    const root = try allocator.dupe(u8, root_raw);
-
-    // Relative path from root to the portfolio file.
-    const rel_raw = if (std.mem.startsWith(u8, abs_path, root) and abs_path.len > root.len)
-        std.mem.trimLeft(u8, abs_path[root.len..], "/")
-    else
-        std.fs.path.basename(abs_path);
-    const rel = try allocator.dupe(u8, rel_raw);
-
-    return .{ .root = root, .rel_path = rel };
-}
-
-/// Inspect the portfolio file's git status. Only the portfolio file is
-/// considered (via pathspec); untracked files elsewhere in the repo are
-/// ignored. Returns one of:
-///   - `.modified`: tracked and has unstaged and/or staged changes
-///   - `.clean`: tracked and matches HEAD (no uncommitted changes)
-///   - `.untracked`: not yet added to the repo (no HEAD version to diff against)
-const PathStatus = enum { modified, clean, untracked };
-
-fn pathStatus(allocator: std.mem.Allocator, root: []const u8, rel_path: []const u8) !PathStatus {
-    const result = std.process.Child.run(.{
-        .allocator = allocator,
-        .argv = &.{ "git", "-C", root, "status", "--porcelain", "--", rel_path },
-        .max_output_bytes = 64 * 1024,
-    }) catch return error.GitUnavailable;
-
-    switch (result.term) {
-        .Exited => |code| if (code != 0) return error.GitStatusFailed,
-        else => return error.GitStatusFailed,
-    }
-
-    const trimmed = std.mem.trim(u8, result.stdout, " \t\r\n");
-    if (trimmed.len == 0) return .clean;
-    // Porcelain format: "XY <path>" where X is index status, Y is worktree status.
-    // "??" means untracked. Anything else with at least one non-space is a modification.
-    if (trimmed.len >= 2 and trimmed[0] == '?' and trimmed[1] == '?') return .untracked;
-    return .modified;
-}
-
-/// Run `git show <rev>:<path>` and return the stdout bytes.
-fn gitShow(allocator: std.mem.Allocator, root: []const u8, rev: []const u8, rel_path: []const u8) ![]const u8 {
-    // Build "<rev>:<rel_path>".
-    const spec = try std.fmt.allocPrint(allocator, "{s}:{s}", .{ rev, rel_path });
-
-    const result = std.process.Child.run(.{
-        .allocator = allocator,
-        .argv = &.{ "git", "-C", root, "show", spec },
-        .max_output_bytes = 32 * 1024 * 1024,
-    }) catch return error.GitUnavailable;
-
-    switch (result.term) {
-        .Exited => |code| {
-            if (code != 0) {
-                // Distinguish "no such revision" from "path missing".
-                if (std.mem.indexOf(u8, result.stderr, "unknown revision") != null or
-                    std.mem.indexOf(u8, result.stderr, "bad revision") != null or
-                    std.mem.indexOf(u8, result.stderr, "ambiguous argument") != null)
-                {
-                    return error.UnknownRevision;
-                }
-                if (std.mem.indexOf(u8, result.stderr, "does not exist") != null or
-                    std.mem.indexOf(u8, result.stderr, "exists on disk, but not in") != null)
-                {
-                    return error.PathMissingInRev;
-                }
-                return error.GitShowFailed;
-            }
-        },
-        else => return error.GitShowFailed,
-    }
-
-    return result.stdout;
-}
 
 // ── Diff algorithm ───────────────────────────────────────────