package mcpsrv_test

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

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"

	"sourcecraft.dev/bigbes/sr-ht-core/auth"

	"sourcecraft.dev/bigbes/sr-ht-dolt/core"
	"sourcecraft.dev/bigbes/sr-ht-dolt/mcpsrv"
)

// The generic tools of docs/DESIGN.mcp.md §9.1, driven through the same
// in-process MCP client the rest of the suite uses (mcpsrv_test.go carries the
// fixtures, the fakes and the plumbing).
//
// Three properties are worth more than the rest here and each has a section of
// its own below: a database the caller may not read answers exactly as one that
// does not exist; a page that stopped short says so and says how far it had to
// go; and a ref or a table that is not there is an answer *about* a database the
// caller is looking straight at, not the masked refusal.

// --- the shapes a client decodes --------------------------------------------
//
// Spelled out here rather than exported from the package: they are this
// surface's contract, and a test that reused the production structs would pass
// no matter what those structs said.

type (
	branchResult struct {
		Name string `json:"name"`
		Head string `json:"head"`
	}

	listBranchesResult struct {
		Branches      []branchResult `json:"branches"`
		DefaultBranch string         `json:"default_branch"`
	}

	columnResult struct {
		Name       string `json:"name"`
		Type       string `json:"type"`
		PrimaryKey bool   `json:"primary_key"`
		Nullable   bool   `json:"nullable"`
	}

	tableResult struct {
		Name     string         `json:"name"`
		Columns  []columnResult `json:"columns"`
		RowCount uint64         `json:"row_count"`
	}

	listTablesResult struct {
		Ref    string        `json:"ref"`
		Tables []tableResult `json:"tables"`
	}

	readRowsResult struct {
		Ref       string     `json:"ref"`
		Table     string     `json:"table"`
		Columns   []string   `json:"columns"`
		Rows      [][]string `json:"rows"`
		Offset    int        `json:"offset"`
		Limit     int        `json:"limit"`
		Total     int        `json:"total"`
		Truncated bool       `json:"truncated"`
	}

	commitResult struct {
		Hash    string    `json:"hash"`
		Author  string    `json:"author"`
		Date    time.Time `json:"date"`
		Message string    `json:"message"`
		Parents []string  `json:"parents"`
	}

	commitLogResult struct {
		Ref       string         `json:"ref"`
		Commits   []commitResult `json:"commits"`
		Next      string         `json:"next"`
		Limit     int            `json:"limit"`
		Truncated bool           `json:"truncated"`
	}

	tableDiffResult struct {
		Name          string `json:"name"`
		Added         bool   `json:"added"`
		Dropped       bool   `json:"dropped"`
		SchemaChanged bool   `json:"schema_changed"`
		RowsAdded     int64  `json:"rows_added"`
		RowsRemoved   int64  `json:"rows_removed"`
		RowsModified  int64  `json:"rows_modified"`
	}

	commitDiffResult struct {
		Hash   string            `json:"hash"`
		Tables []tableDiffResult `json:"tables"`
	}
)

// args addresses ~alice/<name> and adds the key/value pairs given, so that a
// call in a test reads as the one argument it is actually about.
func args(name string, kv ...any) map[string]any {
	if len(kv)%2 != 0 {
		panic("args: odd key/value list")
	}
	out := map[string]any{"owner": "alice", "name": name}
	for i := 0; i < len(kv); i += 2 {
		out[kv[i].(string)] = kv[i+1]
	}
	return out
}

func anonSession(t *testing.T) *mcp.ClientSession {
	t.Helper()
	return connect(t, newServer(t, newFakeRepos(), newFakeOpener()), nil)
}

func readRows(t *testing.T, s *mcp.ClientSession, a map[string]any) readRowsResult {
	t.Helper()
	var out readRowsResult
	decode(t, call(t, s, "read_rows", a), &out)
	return out
}

func commitLog(t *testing.T, s *mcp.ClientSession, a map[string]any) commitLogResult {
	t.Helper()
	var out commitLogResult
	decode(t, call(t, s, "get_commit_log", a), &out)
	return out
}

// --- what each tool answers -------------------------------------------------

func TestListBranchesNamesEveryBranchAndTheDefault(t *testing.T) {
	var out listBranchesResult
	decode(t, call(t, anonSession(t), "list_branches", args("notes")), &out)

	assert.ElementsMatch(t, []branchResult{
		{Name: "main", Head: "aaaa"},
		{Name: "wip", Head: "c001"},
	}, out.Branches)
	assert.Equal(t, "main", out.DefaultBranch,
		"the default is browse.DefaultBranch's answer, reported so a caller need not reimplement the rule")
}

// A database nothing has been pushed to has no branches, and that is an answer:
// an empty list and an empty default, not a failure and not a refusal.
func TestListBranchesOfADatabaseWithNoCommits(t *testing.T) {
	res := call(t, anonSession(t), "list_branches", args("empty"))
	require.False(t, res.IsError, "%s", errorText(res))

	var out listBranchesResult
	decode(t, res, &out)
	assert.Empty(t, out.Branches)
	assert.Empty(t, out.DefaultBranch)
}

func TestListTablesReportsSchemaAndRowCounts(t *testing.T) {
	var out listTablesResult
	decode(t, call(t, anonSession(t), "list_tables", args("notes")), &out)

	assert.Equal(t, "main", out.Ref)
	require.Len(t, out.Tables, 2)

	byName := map[string]tableResult{}
	for _, tbl := range out.Tables {
		byName[tbl.Name] = tbl
	}
	require.Contains(t, byName, "notes")
	assert.EqualValues(t, notesRows, byName["notes"].RowCount)
	assert.EqualValues(t, 3, byName["tags"].RowCount)
	assert.Equal(t, []columnResult{
		{Name: "id", Type: "int", PrimaryKey: true, Nullable: false},
		{Name: "body", Type: "text", PrimaryKey: false, Nullable: true},
	}, byName["notes"].Columns)
}

// An omitted ref is the database's default branch, and the answer names the one
// it read — so an agent that did not care about branches learns which it is
// looking at and can pin it for the rest of a series of calls.
func TestRefDefaultsToTheDefaultBranch(t *testing.T) {
	server := newServer(t, newFakeRepos(), newFakeOpener())

	t.Run("omitted", func(t *testing.T) {
		var out listTablesResult
		decode(t, call(t, connect(t, server, nil), "list_tables", args("notes")), &out)
		assert.Equal(t, "main", out.Ref)
	})

	t.Run("named", func(t *testing.T) {
		var out listTablesResult
		decode(t, call(t, connect(t, server, nil), "list_tables", args("notes", "ref", "wip")), &out)
		assert.Equal(t, "wip", out.Ref)
	})

	// browse.DefaultBranch falls back to the first branch by name when there is
	// no "main", and this database has only a "release" — the fallback is the
	// rule, not an accident of the other fixtures all being called "main".
	t.Run("a database with no main", func(t *testing.T) {
		var out listTablesResult
		decode(t, call(t, connect(t, server, bob()), "list_tables", args("secrets")), &out)
		assert.Equal(t, "release", out.Ref)
	})

	// read_rows and get_commit_log default the same way, and each one is asked
	// rather than assumed to share an implementation.
	t.Run("read_rows", func(t *testing.T) {
		got := readRows(t, connect(t, server, nil), args("notes", "table", "notes"))
		assert.Equal(t, "main", got.Ref)
	})

	t.Run("get_commit_log", func(t *testing.T) {
		got := commitLog(t, connect(t, server, nil), args("notes"))
		assert.Equal(t, "main", got.Ref)
	})
}

// A database with no branches has no default to fall back to. That is a sentence
// the agent reads — nothing has been pushed yet — and not a protocol failure, and
// not the masked "no such database" either: the database is right there.
func TestADatabaseWithNoBranchesHasNothingToReadAt(t *testing.T) {
	server := newServer(t, newFakeRepos(), newFakeOpener())

	for _, tc := range []struct {
		tool string
		args map[string]any
	}{
		{"list_tables", args("empty")},
		{"read_rows", args("empty", "table", "notes")},
		{"get_commit_log", args("empty")},
	} {
		t.Run(tc.tool, func(t *testing.T) {
			res := call(t, connect(t, server, nil), tc.tool, tc.args)
			require.True(t, res.IsError)

			text := errorText(res)
			assert.Contains(t, text, "~alice/empty")
			assert.Contains(t, text, "no branches")
			assert.NotContains(t, text, "no database",
				"the database exists and the caller may read it; only its history is missing")
		})
	}
}

func TestReadRowsAnswersAPageAndTheTotal(t *testing.T) {
	got := readRows(t, anonSession(t), args("notes", "table", "notes"))

	assert.Equal(t, "main", got.Ref)
	assert.Equal(t, "notes", got.Table)
	assert.Equal(t, []string{"id", "body"}, got.Columns)
	assert.Equal(t, 0, got.Offset)
	assert.Equal(t, 100, got.Limit, "the default of docs/DESIGN.mcp.md §9.3")
	assert.Len(t, got.Rows, 100)
	assert.Equal(t, []string{"0", "notes row 0"}, got.Rows[0])
	assert.Equal(t, notesRows, got.Total, "the denominator is the whole table, not the page")
	assert.True(t, got.Truncated, "1100 rows are left behind and the caller cannot see the table")
}

func TestReadRowsPagesByOffset(t *testing.T) {
	session := anonSession(t)

	t.Run("a page in the middle", func(t *testing.T) {
		got := readRows(t, session, args("notes", "table", "notes", "offset", 500, "limit", 10))
		assert.Equal(t, 500, got.Offset)
		require.Len(t, got.Rows, 10)
		assert.Equal(t, []string{"500", "notes row 500"}, got.Rows[0])
		assert.True(t, got.Truncated)
	})

	t.Run("the last page is not truncated", func(t *testing.T) {
		got := readRows(t, session, args("notes", "table", "notes", "offset", notesRows-10, "limit", 100))
		assert.Len(t, got.Rows, 10)
		assert.Equal(t, notesRows, got.Total)
		assert.False(t, got.Truncated, "nothing follows this page, so nothing was left behind")
	})

	// Past the end is an empty page with the true total, which is how a caller
	// that paged one step too far learns it did rather than concluding the table
	// emptied out.
	t.Run("past the end", func(t *testing.T) {
		got := readRows(t, session, args("notes", "table", "notes", "offset", notesRows+50))
		assert.Empty(t, got.Rows)
		assert.Equal(t, notesRows, got.Total)
		assert.False(t, got.Truncated)
	})
}

// The cap of docs/DESIGN.mcp.md §9.3 is applied and *stated*: the answer carries
// the limit that was really used and the total it stopped short of, so a caller
// asking for 5000 rows can tell what it got.
func TestReadRowsCapsTheLimitAndSaysSo(t *testing.T) {
	got := readRows(t, anonSession(t), args("notes", "table", "notes", "limit", 5000))

	assert.Equal(t, 500, got.Limit, "the cap, reported rather than silently applied")
	assert.Len(t, got.Rows, 500)
	assert.Equal(t, notesRows, got.Total)
	assert.True(t, got.Truncated)
}

// A limit of zero or less is refused rather than defaulted: the caller typed a
// number, and answering a default page would make the result a statement about a
// request nobody made. An empty page would read as an empty table.
func TestReadRowsRefusesANonPositivePage(t *testing.T) {
	session := anonSession(t)

	for _, limit := range []int{0, -1} {
		res := call(t, session, "read_rows", args("notes", "table", "notes", "limit", limit))
		require.True(t, res.IsError, "limit %d", limit)
		assert.Contains(t, errorText(res), "limit must be a positive number of rows")
	}

	res := call(t, session, "read_rows", args("notes", "table", "notes", "offset", -3))
	require.True(t, res.IsError)
	assert.Contains(t, errorText(res), "offset must be zero or more")
}

func TestReadRowsNeedsATable(t *testing.T) {
	res := call(t, anonSession(t), "read_rows", args("notes", "table", ""))
	require.True(t, res.IsError)
	assert.Contains(t, errorText(res), "table")
}

func TestGetCommitLogAnswersNewestFirst(t *testing.T) {
	got := commitLog(t, anonSession(t), args("notes"))

	assert.Equal(t, "main", got.Ref)
	assert.Equal(t, 25, got.Limit, "the default of docs/DESIGN.mcp.md §9.3")
	require.Len(t, got.Commits, 25)

	head := got.Commits[0]
	assert.Equal(t, "aaaa", head.Hash)
	assert.Equal(t, "alice", head.Author)
	assert.Equal(t, "commit 0", head.Message)
	assert.True(t, headTime.Equal(head.Date), "got %v", head.Date)
	assert.Equal(t, []string{"c001"}, head.Parents)
}

// The commit log has no total — counting one means walking the whole graph — so
// the cursor is what tells a full answer from a clipped one, and it has to
// actually continue the page.
func TestGetCommitLogPagesWithACursor(t *testing.T) {
	session := anonSession(t)

	first := commitLog(t, session, args("notes"))
	require.True(t, first.Truncated)
	require.NotEmpty(t, first.Next)

	second := commitLog(t, session, args("notes", "from", first.Next))
	require.NotEmpty(t, second.Commits)
	assert.Equal(t, first.Next, second.Commits[0].Hash, "the cursor is where the next page starts")
	assert.Empty(t, second.Ref,
		"a from-hash is a point in the graph, and claiming it belongs to a branch would be unchecked")

	last := commitLog(t, session, args("notes", "from", "c149"))
	assert.False(t, last.Truncated, "the initial commit is the end of the history")
	assert.Empty(t, last.Next)
	require.Len(t, last.Commits, 1)
	assert.Equal(t, []string{}, last.Commits[0].Parents,
		"an empty array rather than null, so an agent can loop without a nil check")
}

func TestGetCommitLogCapsTheLimitAndSaysSo(t *testing.T) {
	got := commitLog(t, anonSession(t), args("notes", "limit", 500))

	assert.Equal(t, 100, got.Limit, "the cap of docs/DESIGN.mcp.md §9.3")
	assert.Len(t, got.Commits, 100)
	assert.True(t, got.Truncated)
	assert.NotEmpty(t, got.Next)
}

func TestGetCommitLogRefusesANonPositiveLimit(t *testing.T) {
	session := anonSession(t)

	for _, limit := range []int{0, -5} {
		res := call(t, session, "get_commit_log", args("notes", "limit", limit))
		require.True(t, res.IsError, "limit %d", limit)
		assert.Contains(t, errorText(res), "limit must be a positive number of commits")
	}
}

func TestGetCommitLogReadsTheRefItIsGiven(t *testing.T) {
	got := commitLog(t, anonSession(t), args("notes", "ref", "wip", "limit", 3))

	assert.Equal(t, "wip", got.Ref)
	require.NotEmpty(t, got.Commits)
	assert.Equal(t, "c001", got.Commits[0].Hash, "the head of that branch, not of the default one")
}

// The initial commit is compared against an empty database, so every table reads
// as added — the one case where a diff describes the whole database rather than a
// change to it.
func TestGetCommitDiffOnTheInitialCommit(t *testing.T) {
	var out commitDiffResult
	decode(t, call(t, anonSession(t), "get_commit_diff", args("notes", "hash", "c149")), &out)

	assert.Equal(t, "c149", out.Hash)
	require.Len(t, out.Tables, 2)
	for _, tbl := range out.Tables {
		assert.True(t, tbl.Added, "%s reads as added against the empty root", tbl.Name)
		assert.False(t, tbl.Dropped, "%s", tbl.Name)
		assert.Zero(t, tbl.RowsRemoved, "%s", tbl.Name)
	}

	byName := map[string]tableDiffResult{}
	for _, tbl := range out.Tables {
		byName[tbl.Name] = tbl
	}
	assert.EqualValues(t, notesRows, byName["notes"].RowsAdded)
	assert.EqualValues(t, 3, byName["tags"].RowsAdded)
}

// A branch name is accepted and means its head, and the answer carries the
// resolved hash — which pins what was summarized even if the branch moves a
// moment later.
func TestGetCommitDiffResolvesABranchName(t *testing.T) {
	var out commitDiffResult
	decode(t, call(t, anonSession(t), "get_commit_diff", args("notes", "hash", "main")), &out)

	assert.Equal(t, "aaaa", out.Hash)
	require.Len(t, out.Tables, 1)
	assert.Equal(t, "notes", out.Tables[0].Name)
	assert.EqualValues(t, 2, out.Tables[0].RowsAdded)
	assert.EqualValues(t, 1, out.Tables[0].RowsModified)
}

func TestGetCommitDiffNeedsACommit(t *testing.T) {
	res := call(t, anonSession(t), "get_commit_diff", args("notes", "hash", ""))
	require.True(t, res.IsError)
	assert.Contains(t, errorText(res), "commit")
}

// --- the two kinds of miss --------------------------------------------------

// A ref that resolves to neither a branch nor a commit is an ordinary answer
// about a database the caller is looking straight at: it names the ref, names
// the database, and is not the masked refusal. Masking it instead would send an
// agent off to re-resolve a database that is right there, over a typo.
func TestAnUnresolvableRefIsAnAnswerAboutTheDatabase(t *testing.T) {
	server := newServer(t, newFakeRepos(), newFakeOpener())

	for _, tc := range []struct {
		tool string
		args map[string]any
	}{
		{"list_tables", args("notes", "ref", "nope")},
		{"read_rows", args("notes", "table", "notes", "ref", "nope")},
		{"get_commit_log", args("notes", "ref", "nope")},
	} {
		t.Run(tc.tool, func(t *testing.T) {
			res := call(t, connect(t, server, nil), tc.tool, tc.args)
			require.True(t, res.IsError)

			text := errorText(res)
			assert.Contains(t, text, "nope")
			assert.Contains(t, text, "~alice/notes")
			assert.NotContains(t, text, "no database", "this is not the masked not-found")
		})
	}
}

func TestAMissingTableIsAnAnswerAboutTheDatabase(t *testing.T) {
	res := call(t, anonSession(t), "read_rows", args("notes", "table", "ghosts"))
	require.True(t, res.IsError)

	text := errorText(res)
	assert.Contains(t, text, "ghosts")
	assert.Contains(t, text, "~alice/notes")
	assert.Contains(t, text, "main", "and says where it looked")
	assert.NotContains(t, text, "no database")
}

func TestAnUnknownCommitIsAnAnswerAboutTheDatabase(t *testing.T) {
	res := call(t, anonSession(t), "get_commit_diff", args("notes", "hash", "deadbeef"))
	require.True(t, res.IsError)

	text := errorText(res)
	assert.Contains(t, text, "deadbeef")
	assert.Contains(t, text, "~alice/notes")
	assert.NotContains(t, text, "no database")
}

// --- the visibility matrix --------------------------------------------------

// browseTarget is one fixture database with arguments valid for it, so that the
// matrix below exercises every tool against every visibility rather than only
// the ones that need no table or commit.
type browseTarget struct {
	db     string
	table  string
	commit string
}

func browseTargets() []browseTarget {
	return []browseTarget{
		{db: "notes", table: "notes", commit: "aaaa"},     // PUBLIC
		{db: "drafts", table: "drafts", commit: "dddd"},   // UNLISTED
		{db: "secrets", table: "secrets", commit: "eeee"}, // PRIVATE, bob is granted RO
	}
}

// browseCall is one tool and the arguments it needs for a given database, so
// that a property worth holding for the whole chapter can be written once and
// asserted for every tool of it.
type browseCall struct {
	name string
	args func(browseTarget) map[string]any
}

// browseTools is every tool of docs/DESIGN.mcp.md §9.1 that addresses a single
// database — which is all of them; list_databases addresses none and is the
// other suite's.
func browseTools() []browseCall {
	return []browseCall{
		{"list_branches", func(tg browseTarget) map[string]any { return args(tg.db) }},
		{"list_tables", func(tg browseTarget) map[string]any { return args(tg.db) }},
		{"read_rows", func(tg browseTarget) map[string]any { return args(tg.db, "table", tg.table) }},
		{"get_commit_log", func(tg browseTarget) map[string]any { return args(tg.db) }},
		{"get_commit_diff", func(tg browseTarget) map[string]any { return args(tg.db, "hash", tg.commit) }},
	}
}

// readable is the access matrix of core.Allowed for OpBrowse, spelled out
// independently of the implementation under test: PUBLIC and UNLISTED are
// readable by everyone including anonymity — unlisted hides from a *listing*, not
// from a direct address — and PRIVATE only by its owner and its grantees.
func readable(f fixture, viewer *core.Caller) bool {
	if f.visibility != core.VisibilityPrivate {
		return true
	}
	if viewer == nil {
		return false
	}
	if viewer.UserID == aliceID {
		return true // alice owns every fixture
	}
	_, granted := f.acl[viewer.UserID]
	return granted
}

func fixtureNamed(t *testing.T, name string) fixture {
	t.Helper()
	for _, f := range fixtures() {
		if f.name == name {
			return f
		}
	}
	t.Fatalf("no fixture named %q", name)
	return fixture{}
}

// Every tool, every visibility, every principal: either the tool answers, or the
// database is reported as not existing. There is no third outcome and in
// particular no "forbidden" — a refusal of its own shape is exactly the
// distinction the masked not-found exists to erase (docs/DESIGN.mcp.md §4.3).
//
// The masked answer is compared against the answer for a database that genuinely
// does not exist, with the name substituted: the two must differ by nothing but
// the name the caller itself supplied.
func TestTheVisibilityMatrix(t *testing.T) {
	server := newServer(t, newFakeRepos(), newFakeOpener())

	callers := []struct {
		name string
		ac   *auth.AuthContext
	}{
		{"anonymous", nil},
		{"a stranger", carol()},
		{"a grantee", bob()},
		{"the owner", alice()},
	}

	for _, tool := range browseTools() {
		for _, tg := range browseTargets() {
			for _, who := range callers {
				t.Run(tool.name+"/"+tg.db+"/"+who.name, func(t *testing.T) {
					session := connect(t, server, who.ac)
					res := call(t, session, tool.name, tool.args(tg))

					if readable(fixtureNamed(t, tg.db), coreCaller(who.ac)) {
						assert.False(t, res.IsError, "%s", errorText(res))
						return
					}

					require.True(t, res.IsError, "a database this caller may not read must not answer")

					absent := tg
					absent.db = "nosuch"
					missing := call(t, session, tool.name, tool.args(absent))
					require.True(t, missing.IsError)

					assert.Equal(t,
						strings.Replace(errorText(missing), "nosuch", tg.db, 1),
						errorText(res),
						"a masked database answers exactly as one that does not exist")
				})
			}
		}
	}
}

// Nothing about a database the caller may not read leaks through the refusal —
// not a branch head, not another table's name, not a row. The database's own
// name is in the sentence because the caller put it there: that is the whole
// point of building the sentence from the call's arguments (errors.go).
func TestNothingAboutAMaskedDatabaseLeaks(t *testing.T) {
	server := newServer(t, newFakeRepos(), newFakeOpener())

	for _, tool := range browseTools() {
		tg := browseTarget{db: "secrets", table: "secrets", commit: "eeee"}
		t.Run(tool.name, func(t *testing.T) {
			session := connect(t, server, carol())
			body := resultJSON(t, call(t, session, tool.name, tool.args(tg)))

			assert.NotContains(t, body, "release", "not the branch it has")
			assert.NotContains(t, body, "keys", "not the other table it has")
			assert.NotContains(t, body, "secrets row", "and certainly not a row")
		})
	}
}

// A grantee reads the private database whole: the matrix above proves the tools
// answer, and this proves they answer with its actual contents rather than an
// empty shell.
func TestAGranteeReadsAPrivateDatabase(t *testing.T) {
	session := connect(t, newServer(t, newFakeRepos(), newFakeOpener()), bob())

	got := readRows(t, session, args("secrets", "table", "secrets"))
	assert.Equal(t, "release", got.Ref)
	assert.Equal(t, 3, got.Total)
	require.Len(t, got.Rows, 3)
	assert.Equal(t, []string{"0", "secrets row 0"}, got.Rows[0])
}

// --- addressing, sessions and failures --------------------------------------

// The sigil is what a link shows, so an agent copying an address is more likely
// to include it than not.
func TestABrowseToolToleratesTheSigil(t *testing.T) {
	var out listBranchesResult
	decode(t, call(t, anonSession(t), "list_branches", map[string]any{"owner": "~alice", "name": "notes"}), &out)
	assert.NotEmpty(t, out.Branches)
}

func TestAddressingNeedsBothParts(t *testing.T) {
	session := anonSession(t)

	for _, a := range []map[string]any{
		{"owner": "", "name": "notes"},
		{"owner": "alice", "name": ""},
	} {
		res := call(t, session, "list_branches", a)
		require.True(t, res.IsError, "%v", a)
		assert.Contains(t, errorText(res), "owner")
		assert.Contains(t, errorText(res), "name")
	}
}

// One session per call, closed by the handler that opened it. A store held open
// across calls is a stale manifest and a leaked handle, and a tool that opened a
// database it was not asked about would be reading somebody else's.
func TestEveryToolClosesTheSessionItOpened(t *testing.T) {
	for _, tool := range browseTools() {
		t.Run(tool.name, func(t *testing.T) {
			opener := newFakeOpener()
			session := connect(t, newServer(t, newFakeRepos(), opener), nil)

			call(t, session, tool.name, tool.args(browseTarget{db: "notes", table: "notes", commit: "aaaa"}))

			assert.Equal(t, []string{storePath("alice", "notes")}, opener.opened,
				"exactly the one database the call named")
			assert.Equal(t, 1, opener.sessions[storePath("alice", "notes")].closes)
		})
	}
}

// A store that will not open is a protocol error, not a miss: the database
// exists and the caller may read it, and answering "not found" would be a false
// statement about the data instead of a true one about the server.
func TestAStoreThatWillNotOpenIsAProtocolError(t *testing.T) {
	session := connect(t, newServer(t, newFakeRepos(), newFakeOpener()), nil)

	res, err := session.CallTool(context.Background(), &mcp.CallToolParams{
		Name:      "list_branches",
		Arguments: args("broken"),
	})
	require.Error(t, err, "a store this daemon cannot read is not an answer about the data")
	assert.Nil(t, res)
	assert.NotContains(t, err.Error(), "/stores", "and the cause is logged, not sent")
}

// No raw browse error text ever reaches a caller: it carries dolt internals and
// on-disk paths, and this endpoint is reachable by anyone holding any valid
// token — or by nobody at all.
func TestABrowseFailureDisclosesNoDetail(t *testing.T) {
	const detail = "read /srv/dolt/~alice/notes/manifest: input/output error"

	for _, tc := range []struct {
		tool string
		args map[string]any
		// fail breaks the one call this tool makes into the store.
		fail func(*fakeSession)
	}{
		{"list_tables", args("notes"), func(s *fakeSession) { s.tablesErr = errors.New(detail) }},
		{"read_rows", args("notes", "table", "notes"), func(s *fakeSession) { s.rowsErr = errors.New(detail) }},
		{"get_commit_log", args("notes"), func(s *fakeSession) { s.logErr = errors.New(detail) }},
	} {
		t.Run(tc.tool, func(t *testing.T) {
			opener := newFakeOpener()
			tc.fail(opener.sessions[storePath("alice", "notes")])
			session := connect(t, newServer(t, newFakeRepos(), opener), nil)

			res, err := session.CallTool(context.Background(), &mcp.CallToolParams{
				Name:      tc.tool,
				Arguments: tc.args,
			})
			require.Error(t, err, "a store that could not answer is not an answer")
			assert.Nil(t, res)
			assert.NotContains(t, err.Error(), "/srv/dolt")
			assert.NotContains(t, err.Error(), "input/output error")
		})
	}
}

// An ACL lookup that fails is a protocol error and not a masked not-found. The
// web degrades a failed lookup to "no grant" and falls back to visibility, which
// costs a signed-in user a rendering; here it would tell an agent that a database
// it was granted access to does not exist, and an agent believes that.
func TestAnACLLookupFailureIsNotAMissingDatabase(t *testing.T) {
	repos := &failingACLRepos{fakeRepos: newFakeRepos()}
	session := connect(t, newServer(t, repos, newFakeOpener()), bob())

	res, err := session.CallTool(context.Background(), &mcp.CallToolParams{
		Name:      "list_branches",
		Arguments: args("secrets"),
	})
	require.Error(t, err, `"I could not check" is not "you may not"`)
	assert.Nil(t, res)
	assert.NotContains(t, err.Error(), "5432", "the cause is logged, not sent")
}

// failingACLRepos is the metadata store with a working repository lookup and a
// broken ACL one, which is the shape of a partial database outage.
type failingACLRepos struct {
	*fakeRepos
}

var _ mcpsrv.Repos = (*failingACLRepos)(nil)

func (f *failingACLRepos) EffectiveAccess(context.Context, int, int) (*core.AccessMode, error) {
	return nil, errors.New("dial tcp 127.0.0.1:5432: connection refused")
}