package gitx

import (
	"context"
	"errors"
	"strings"
	"testing"

	"sourcecraft.dev/bigbes/sr-ht-spec/core"
)

func TestCreateProposalBranch(t *testing.T) {
	repo, _ := newSpace(t)
	ctx := context.Background()

	base := pushApproved(t, repo, ownerMeta("seed", 1),
		Write{Path: "specs/0007.md", Content: doc("SPEC-0007", "Storage", "v1")})

	head, err := repo.CreateProposalBranch(ctx, "proposals/1", base.String())
	if err != nil {
		t.Fatalf("CreateProposalBranch: %v", err)
	}
	if head != base {
		t.Fatalf("branch cut at %s, want the base %s", head, base)
	}
	got, err := repo.BranchHead(ctx, "proposals/1")
	if err != nil {
		t.Fatalf("BranchHead: %v", err)
	}
	if got != base {
		t.Fatalf("proposals/1 = %s, want %s", got, base)
	}

	// Cutting the same branch twice is a caller bug, not an idempotent retry:
	// the second call would silently discard whatever the first accumulated.
	if _, err := repo.CreateProposalBranch(ctx, "proposals/1", base.String()); !errors.Is(err, ErrExists) {
		t.Fatalf("second CreateProposalBranch = %v, want ErrExists", err)
	}
	// Only proposals/* branches exist to be cut.
	for _, b := range []string{"main", "scratch", "proposals", ""} {
		if _, err := repo.CreateProposalBranch(ctx, b, base.String()); !errors.Is(err, ErrBadRev) {
			t.Fatalf("CreateProposalBranch(%q) = %v, want ErrBadRev", b, err)
		}
	}
	if _, err := repo.CreateProposalBranch(ctx, "proposals/2", "nosuchrev"); !errors.Is(err, ErrNotFound) {
		t.Fatalf("CreateProposalBranch at an unknown base = %v, want ErrNotFound", err)
	}
}

func TestCommitProposalSplicesWholeDocuments(t *testing.T) {
	repo, _ := newSpace(t)
	ctx := context.Background()

	base := pushApproved(t, repo, ownerMeta("seed", 1),
		Write{Path: "specs/0007.md", Content: doc("SPEC-0007", "Storage", "v1")},
		Write{Path: "specs/deep/nested/0008.md", Content: doc("SPEC-0008", "Nested", "n1")},
		Write{Path: "specs/diagram.png", Content: []byte{0x89, 'P', 'N', 'G'}},
	)
	if _, err := repo.CreateProposalBranch(ctx, "proposals/1", base.String()); err != nil {
		t.Fatal(err)
	}

	res, err := repo.CommitProposal(ctx, "proposals/1", []Write{
		{Path: "specs/0007.md", Content: doc("SPEC-0007", "Storage", "v2")},
		{Path: "notes/new.md", Content: doc("NOTE-0001", "New", "fresh")},
	}, meta("revise 0007 and add a note", 2,
		Trailer{Key: "X-Agent-Session", Value: "8fb9c9a4"},
		Trailer{Key: "X-Agent-Base", Value: base.String()},
	))
	if err != nil {
		t.Fatalf("CommitProposal: %v", err)
	}

	if len(res.Parents) != 1 || res.Parents[0] != base {
		t.Fatalf("parents = %v, want [%s]", res.Parents, base)
	}
	if len(res.Blobs) != 2 {
		t.Fatalf("Blobs = %v, want one per write", res.Blobs)
	}

	c, err := repo.repo.CommitObject(res.Commit)
	if err != nil {
		t.Fatal(err)
	}
	// Author is the agent, committer the owner: the provenance the design
	// requires, supplied whole by the caller.
	if !strings.HasPrefix(c.Author.Name, "claude-code/") || c.Committer.Name != "bigbes" {
		t.Fatalf("identities = author %q, committer %q", c.Author.Name, c.Committer.Name)
	}
	wantMsg := "revise 0007 and add a note\n\nX-Agent-Session: 8fb9c9a4\nX-Agent-Base: " + base.String() + "\n"
	if c.Message != wantMsg {
		t.Fatalf("message = %q, want %q", c.Message, wantMsg)
	}

	// The splice replaced one document, added another, and left everything else
	// — including the nested subtree and the attachment — exactly as it was.
	if got := mustRead(t, repo, "proposals/1", "specs/0007.md"); !strings.Contains(got, "v2") {
		t.Fatalf("edited document = %q", got)
	}
	if got := mustRead(t, repo, "proposals/1", "notes/new.md"); !strings.Contains(got, "fresh") {
		t.Fatalf("added document = %q", got)
	}
	if got := mustRead(t, repo, "proposals/1", "specs/deep/nested/0008.md"); !strings.Contains(got, "n1") {
		t.Fatalf("untouched nested document = %q", got)
	}
	png, _, err := repo.ReadBlob(ctx, "proposals/1", "specs/diagram.png")
	if err != nil || len(png) != 4 {
		t.Fatalf("attachment survived as %v, %v", png, err)
	}
	// The approved branch did not move.
	if head, _ := repo.ApprovedHead(ctx); head != base {
		t.Fatalf("a proposal commit moved the approved branch to %s", head)
	}
}

// TestCommitProposalRefusesTheApprovedBranch is the second half of the refs
// rule, enforced in-process: the approved branch moves by a human push or by
// Merge, and by nothing else.
func TestCommitProposalRefusesTheApprovedBranch(t *testing.T) {
	repo, _ := newSpace(t)
	ctx := context.Background()

	w := []Write{{Path: "specs/0007.md", Content: doc("SPEC-0007", "Storage", "v1")}}
	for _, branch := range []string{DefaultApprovedBranch, "scratch", "proposals", "refs/heads/proposals/1"} {
		_, err := repo.CommitProposal(ctx, branch, w, meta("nope", 2))
		if !errors.Is(err, ErrBadRev) {
			t.Fatalf("CommitProposal(%q) = %v, want ErrBadRev", branch, err)
		}
	}
}

func TestCommitProposalValidatesItsWrites(t *testing.T) {
	repo, _ := newSpace(t)
	ctx := context.Background()

	base, err := repo.ApprovedHead(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if _, err := repo.CreateProposalBranch(ctx, "proposals/1", base.String()); err != nil {
		t.Fatal(err)
	}
	good := doc("SPEC-0007", "Storage", "v1")

	// Only document paths. .spec.yml is a real file in a space but it is not a
	// document, and the write plane is a whole-document PUT.
	for _, p := range []string{core.PolicyFile, "specs/0007.txt", "../escape.md", "/abs.md", ""} {
		_, err := repo.CommitProposal(ctx, "proposals/1", []Write{{Path: p, Content: good}}, meta("bad path", 2))
		if !errors.Is(err, core.ErrInvalidPath) {
			t.Fatalf("CommitProposal to %q = %v, want core.ErrInvalidPath", p, err)
		}
	}
	// A commit with nothing in it is a caller bug.
	if _, err := repo.CommitProposal(ctx, "proposals/1", nil, meta("empty", 2)); err == nil {
		t.Fatal("CommitProposal with no writes succeeded")
	}
	// The same path twice in one commit: the second would silently win.
	_, err = repo.CommitProposal(ctx, "proposals/1", []Write{
		{Path: "specs/0007.md", Content: good},
		{Path: "specs/0007.md", Content: doc("SPEC-0007", "Storage", "v2")},
	}, meta("twice", 2))
	if err == nil {
		t.Fatal("CommitProposal writing one path twice succeeded")
	}
	// Identities are required.
	if _, err := repo.CommitProposal(ctx, "proposals/1", []Write{{Path: "specs/0007.md", Content: good}},
		CommitMeta{Message: "no identity"}); err == nil {
		t.Fatal("CommitProposal with no identities succeeded")
	}
	// The branch has to exist first.
	if _, err := repo.CommitProposal(ctx, "proposals/9", []Write{{Path: "specs/0007.md", Content: good}},
		meta("absent", 2)); !errors.Is(err, ErrNotFound) {
		t.Fatalf("CommitProposal to an absent branch = %v, want ErrNotFound", err)
	}
}

func TestCommitProposalAccumulatesEdits(t *testing.T) {
	repo, _ := newSpace(t)
	ctx := context.Background()

	base, err := repo.ApprovedHead(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if _, err := repo.CreateProposalBranch(ctx, "proposals/1", base.String()); err != nil {
		t.Fatal(err)
	}
	first, err := repo.CommitProposal(ctx, "proposals/1",
		[]Write{{Path: "notes/a.md", Content: doc("NOTE-0001", "A", "one")}}, meta("first", 2))
	if err != nil {
		t.Fatal(err)
	}
	second, err := repo.CommitProposal(ctx, "proposals/1",
		[]Write{{Path: "notes/b.md", Content: doc("NOTE-0002", "B", "two")}}, meta("second", 3))
	if err != nil {
		t.Fatal(err)
	}
	if second.Parents[0] != first.Commit {
		t.Fatalf("second commit parent = %s, want %s", second.Parents[0], first.Commit)
	}
	paths := docPaths(t, repo, "proposals/1")
	if strings.Join(paths, ",") != "notes/a.md,notes/b.md" {
		t.Fatalf("proposal branch holds %v", paths)
	}
}

func TestCommitProposalRetriesALostRefCAS(t *testing.T) {
	repo, _ := newSpace(t)
	ctx := context.Background()

	base, err := repo.ApprovedHead(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if _, err := repo.CreateProposalBranch(ctx, "proposals/1", base.String()); err != nil {
		t.Fatal(err)
	}
	var raced bool
	repo.beforeCAS = func() {
		if raced {
			return
		}
		raced = true
		pushBranch(t, repo, "proposals/1", meta("someone else", 3),
			Write{Path: "notes/other.md", Content: doc("NOTE-0009", "Other", "landed first")})
	}
	res, err := repo.CommitProposal(ctx, "proposals/1",
		[]Write{{Path: "notes/a.md", Content: doc("NOTE-0001", "A", "one")}}, meta("mine", 4))
	if err != nil {
		t.Fatalf("CommitProposal that lost a CAS = %v, want a retry", err)
	}
	if !raced {
		t.Fatal("the race hook never fired")
	}
	if res.Parents[0] == base {
		t.Fatal("the retry kept the stale parent instead of rebuilding")
	}
	paths := docPaths(t, repo, "proposals/1")
	if strings.Join(paths, ",") != "notes/a.md,notes/other.md" {
		t.Fatalf("proposal branch holds %v; the concurrent write was lost", paths)
	}
}

func TestMutableTreeRefusesFileDirectoryCollisions(t *testing.T) {
	repo, _ := newSpace(t)

	h, err := repo.writeBlob("x", []byte("x"))
	if err != nil {
		t.Fatal(err)
	}
	n := newMutableTree()
	if err := n.set("specs/0007.md", h); err != nil {
		t.Fatal(err)
	}
	// "specs/0007.md" is a file, so it cannot also be a directory...
	if err := n.set("specs/0007.md/inner.md", h); err == nil {
		t.Fatal("set under an existing file succeeded")
	}
	// ...and "specs" is a directory, so it cannot also be a file.
	if err := n.set("specs", h); err == nil {
		t.Fatal("set over an existing directory succeeded")
	}
}

func TestMutableTreeDropsEmptySubtrees(t *testing.T) {
	repo, _ := newSpace(t)

	h, err := repo.writeBlob("x", []byte("x"))
	if err != nil {
		t.Fatal(err)
	}
	n := newMutableTree()
	if err := n.set("a/b/c.md", h); err != nil {
		t.Fatal(err)
	}
	withChild, err := n.write(repo.repo.Storer)
	if err != nil {
		t.Fatal(err)
	}
	if !n.remove("a/b/c.md") {
		t.Fatal("remove reported nothing removed")
	}
	if n.remove("a/b/c.md") {
		t.Fatal("remove reported a second removal")
	}
	empty, err := n.write(repo.repo.Storer)
	if err != nil {
		t.Fatal(err)
	}
	if empty == withChild {
		t.Fatal("emptying the tree did not change its hash")
	}
	tree, err := repo.repo.TreeObject(empty)
	if err != nil {
		t.Fatal(err)
	}
	if len(tree.Entries) != 0 {
		t.Fatalf("empty subtrees survived: %+v", tree.Entries)
	}
}