package validation

import (
	"bytes"
	"context"
	"errors"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
)

func TestReadCandidateTreeUsesCapturedCommitAndEnumeratesGitEntries(t *testing.T) {
	repository := newTreeRepository(t)
	writeTreeFile(t, repository, "README.md", []byte("captured\n"))
	writeTreeFile(t, repository, "vendor/library/go.mod", []byte("module vendor.example\n"))
	writeTreeFile(t, repository, "nested/module/go.mod", []byte("module nested.example\n"))
	writeTreeFile(t, repository, "binary.dat", []byte{0, 1, 255, 2})
	unusualPath := "space tab\tline\nname.txt"
	writeTreeFile(t, repository, unusualPath, []byte("unusual path\n"))
	if err := os.Symlink("README.md", filepath.Join(repository, "readme-link")); err != nil {
		t.Fatal(err)
	}
	submoduleCommit := newTreeRepository(t)
	writeTreeFile(t, submoduleCommit, "sub.txt", []byte("submodule\n"))
	gitTree(t, submoduleCommit, "add", "--all")
	gitTree(t, submoduleCommit, "commit", "-m", "create submodule source")
	submoduleOID := strings.TrimSpace(gitTree(t, submoduleCommit, "rev-parse", "HEAD"))
	gitTree(t, repository, "add", "--all")
	gitTree(t, repository, "update-index", "--add", "--cacheinfo", "160000,"+submoduleOID+",submodule")
	gitTree(t, repository, "commit", "-m", "capture candidate files")
	commit := strings.TrimSpace(gitTree(t, repository, "rev-parse", "HEAD"))

	writeTreeFile(t, repository, "README.md", []byte("worktree changed\n"))
	statusBefore := gitTree(t, repository, "status", "--porcelain=v1", "--untracked-files=all")
	tree, err := ReadCandidateTree(context.Background(), repository, commit)
	if err != nil {
		t.Fatalf("ReadCandidateTree() error = %v", err)
	}
	cleanupCandidateTree(t, tree)
	entries := make(map[string]gitTreeEntry, len(tree.Entries()))
	for _, entry := range tree.Entries() {
		entries[entry.Path] = gitTreeEntry{mode: entry.Mode, kind: entry.Type, size: entry.Size, hasSize: entry.HasSize}
	}
	for _, path := range []string{"vendor/library/go.mod", "nested/module/go.mod", unusualPath} {
		if _, ok := entries[path]; !ok {
			t.Errorf("committed tree is missing %q", path)
		}
	}
	if got := entries["binary.dat"]; got.mode != "100644" || got.kind != "blob" {
		t.Errorf("binary metadata = %#v", got)
	}
	if got := entries["readme-link"]; got.mode != "120000" || got.kind != "blob" {
		t.Errorf("symlink metadata = %#v", got)
	}
	if got := entries["submodule"]; got.mode != "160000" || got.kind != "commit" || got.hasSize {
		t.Errorf("gitlink metadata = %#v", got)
	}
	contents, err := tree.ReadFile(context.Background(), "README.md")
	if err != nil || string(contents) != "captured\n" {
		t.Fatalf("captured README = %q, error = %v", contents, err)
	}
	binary, err := tree.ReadFile(context.Background(), "binary.dat")
	if err != nil || !bytes.Equal(binary, []byte{0, 1, 255, 2}) {
		t.Fatalf("captured binary = %v, error = %v", binary, err)
	}
	unusual, err := tree.ReadFile(context.Background(), unusualPath)
	if err != nil || string(unusual) != "unusual path\n" {
		t.Fatalf("unusual path contents = %q, error = %v", unusual, err)
	}
	if _, err := tree.ReadFile(context.Background(), "submodule"); err == nil {
		t.Fatal("ReadFile() returned submodule commit contents")
	}
	statusAfter := gitTree(t, repository, "status", "--porcelain=v1", "--untracked-files=all")
	if statusAfter != statusBefore {
		t.Fatalf("tree inspection changed worktree state: before %q, after %q", statusBefore, statusAfter)
	}
}

func TestReadCandidateTreeForScopeExcludesNestedModulesAndRetainsFullLookup(t *testing.T) {
	repository := newTreeRepository(t)
	writeTreeFile(t, repository, "COPYRIGHT", []byte("copyright\n"))
	writeTreeFile(t, repository, "LICENSE", []byte("license\n"))
	writeTreeFile(t, repository, "docs/oss/attribution.md", []byte("attribution\n"))
	writeTreeFile(t, repository, "go.mod", []byte("module example.com/root\n"))
	writeTreeFile(t, repository, "root.go", []byte("package root\n"))
	writeTreeFile(t, repository, "parent/go.mod", []byte("module example.com/parent\n"))
	writeTreeFile(t, repository, "parent/main.go", []byte("package parent\n"))
	writeTreeFile(t, repository, "parent/vendor/library/go.mod", []byte("not a boundary\n"))
	writeTreeFile(t, repository, "parent/vendor/library/source.go", []byte("package library\n"))
	writeTreeFile(t, repository, "parent/nested/go.mod", []byte("module example.com/nested\n"))
	writeTreeFile(t, repository, "parent/nested/source.go", []byte("package nested\n"))
	writeTreeFile(t, repository, "sibling/go.mod", []byte("module example.com/sibling\n"))
	writeTreeFile(t, repository, "sibling/source.go", []byte("package sibling\n"))
	commit := commitCandidateTree(t, repository)
	writeTreeFile(t, repository, "parent/worktree-only.go", []byte("package parent\n"))

	tree, err := ReadCandidateTreeForScope(context.Background(), repository, commit, TreeScope{
		ModuleDir: filepath.Join(repository, "parent"),
	})
	if err != nil {
		t.Fatal(err)
	}
	cleanupCandidateTree(t, tree)
	var got []string
	for _, entry := range tree.InputEntries() {
		got = append(got, entry.Path)
	}
	want := []string{
		"COPYRIGHT", "LICENSE", "docs/oss/attribution.md", "parent/go.mod", "parent/main.go",
		"parent/vendor/library/go.mod", "parent/vendor/library/source.go",
	}
	if strings.Join(got, "\n") != strings.Join(want, "\n") {
		t.Fatalf("selected inputs = %q, want %q", got, want)
	}
	if _, ok := tree.Entry("parent/nested/source.go"); !ok {
		t.Fatal("full tree lookup lost an excluded nested module destination")
	}
	destination, err := tree.ResolveDestination(context.Background(), "parent/main.go", "../sibling/source.go")
	if err != nil || destination.Kind != DestinationEntry || destination.Path != "sibling/source.go" {
		t.Fatalf("excluded sibling destination = %#v, %v", destination, err)
	}
	nestedDestination, err := tree.ResolveDestination(context.Background(), "parent/main.go", "nested/source.go")
	if err != nil || nestedDestination.Kind != DestinationEntry || nestedDestination.Path != "parent/nested/source.go" {
		t.Fatalf("excluded nested-module destination = %#v, %v", nestedDestination, err)
	}
	if tree.blobReader != nil || tree.blobReads != 0 {
		t.Fatalf("metadata-only selection read blob content: reader=%v reads=%d", tree.blobReader != nil, tree.blobReads)
	}
}

func TestReadCandidateTreeForRootScopeExcludesNestedModules(t *testing.T) {
	repository := newTreeRepository(t)
	writeTreeFile(t, repository, "go.mod", []byte("module example.com/root\n"))
	writeTreeFile(t, repository, "root.go", []byte("package root\n"))
	writeTreeFile(t, repository, "nested/go.mod", []byte("module example.com/nested\n"))
	writeTreeFile(t, repository, "nested/source.go", []byte("package nested\n"))
	writeTreeFile(t, repository, "vendor/library/go.mod", []byte("not a boundary\n"))
	writeTreeFile(t, repository, "vendor/library/source.go", []byte("package library\n"))
	commit := commitCandidateTree(t, repository)

	tree, err := ReadCandidateTreeForScope(context.Background(), repository, commit, TreeScope{ModuleDir: repository})
	if err != nil {
		t.Fatal(err)
	}
	cleanupCandidateTree(t, tree)
	want := []string{"go.mod", "root.go", "vendor/library/go.mod", "vendor/library/source.go"}
	if got := inputPaths(tree); strings.Join(got, "\n") != strings.Join(want, "\n") {
		t.Fatalf("root module inputs = %q, want %q", got, want)
	}
}

func TestReadCandidateTreeSharedFilesReplaceDefaultsAndDeduplicate(t *testing.T) {
	repository := newTreeRepository(t)
	writeTreeFile(t, repository, "LICENSE", []byte("default\n"))
	writeTreeFile(t, repository, "module/go.mod", []byte("module example.com/module\n"))
	writeTreeFile(t, repository, "module/source.go", []byte("package module\n"))
	writeTreeFile(t, repository, "sibling/shared.txt", []byte("selected explicitly\n"))
	writeTreeFile(t, repository, "literal/*.md", []byte("literal wildcard path\n"))
	commit := commitCandidateTree(t, repository)
	moduleDir := filepath.Join(repository, "module")

	selected, err := ReadCandidateTreeForScope(context.Background(), repository, commit, TreeScope{
		ModuleDir:   moduleDir,
		SharedFiles: []string{"sibling/shared.txt", "module/source.go", "sibling/shared.txt"},
	})
	if err != nil {
		t.Fatal(err)
	}
	cleanupCandidateTree(t, selected)
	var got []string
	for _, entry := range selected.InputEntries() {
		got = append(got, entry.Path)
	}
	want := []string{"module/go.mod", "module/source.go", "sibling/shared.txt"}
	if strings.Join(got, "\n") != strings.Join(want, "\n") {
		t.Fatalf("explicit shared inputs = %q, want %q", got, want)
	}

	empty, err := ReadCandidateTreeForScope(context.Background(), repository, commit, TreeScope{
		ModuleDir:   moduleDir,
		SharedFiles: []string{},
	})
	if err != nil {
		t.Fatal(err)
	}
	cleanupCandidateTree(t, empty)
	if got := inputPaths(empty); strings.Join(got, "\n") != "module/go.mod\nmodule/source.go" {
		t.Fatalf("explicit empty input set = %q", got)
	}

	literal, err := ReadCandidateTreeForScope(context.Background(), repository, commit, TreeScope{
		ModuleDir:   moduleDir,
		SharedFiles: []string{"literal/*.md"},
	})
	if err != nil {
		t.Fatal(err)
	}
	cleanupCandidateTree(t, literal)
	if got := inputPaths(literal); strings.Join(got, "\n") != "literal/*.md\nmodule/go.mod\nmodule/source.go" {
		t.Fatalf("literal wildcard path inputs = %q", got)
	}
}

func TestReadCandidateTreeDefaultsAreOptionalAndExplicitMissingFilesFail(t *testing.T) {
	repository := newTreeRepository(t)
	writeTreeFile(t, repository, "module/go.mod", []byte("module example.com/module\n"))
	writeTreeFile(t, repository, "module/source.go", []byte("package module\n"))
	writeTreeFile(t, repository, "LICENSE", []byte("license\n"))
	commit := commitCandidateTree(t, repository)
	moduleDir := filepath.Join(repository, "module")

	defaults, err := ReadCandidateTreeForScope(context.Background(), repository, commit, TreeScope{ModuleDir: moduleDir})
	if err != nil {
		t.Fatal(err)
	}
	cleanupCandidateTree(t, defaults)
	if got := inputPaths(defaults); strings.Join(got, "\n") != "LICENSE\nmodule/go.mod\nmodule/source.go" {
		t.Fatalf("default shared inputs = %q", got)
	}

	writeTreeFile(t, repository, "missing.md", []byte("present only in the worktree\n"))
	_, err = ReadCandidateTreeForScope(context.Background(), repository, commit, TreeScope{
		ModuleDir:   moduleDir,
		SharedFiles: []string{"missing.md"},
	})
	var failure *Failure
	if !errors.As(err, &failure) || failure.Check != SharedFiles || len(failure.Findings) != 1 || failure.Findings[0].Path != "missing.md" {
		t.Fatalf("missing explicit shared file error = %#v, want path-specific shared-files failure", err)
	}
}

func TestSharedFileSelectionPreservesLiteralBackslash(t *testing.T) {
	if filepath.Separator == '\\' {
		t.Skip("backslash is a filesystem separator on this platform")
	}
	repository := newTreeRepository(t)
	writeTreeFile(t, repository, "module/go.mod", []byte("module example.com/module\n"))
	const name = `docs/notice\copy.txt`
	contents := []byte("literal filename\n")
	writeTreeFile(t, repository, name, contents)
	commit := commitCandidateTree(t, repository)
	moduleDir := filepath.Join(repository, "module")
	tree, err := ReadCandidateTreeForScope(t.Context(), repository, commit, TreeScope{ModuleDir: moduleDir, SharedFiles: []string{name, name}})
	if err != nil {
		t.Fatal(err)
	}
	cleanupCandidateTree(t, tree)
	if got := inputPaths(tree); strings.Join(got, "\n") != name+"\nmodule/go.mod" {
		t.Fatalf("literal selection = %q", got)
	}
	read, err := tree.ReadFile(t.Context(), name)
	if err != nil || string(read) != string(contents) {
		t.Fatalf("literal file content = %q, error = %v", read, err)
	}
	for _, invalid := range []string{"../outside", "/absolute", "docs"} {
		if _, err := ReadCandidateTreeForScope(t.Context(), repository, commit, TreeScope{ModuleDir: moduleDir, SharedFiles: []string{invalid}}); err == nil {
			t.Fatalf("shared selection accepted %q", invalid)
		}
	}
}

func TestRunBuildsInputsOnlyForChecksOrExplicitSharedFiles(t *testing.T) {
	repository := newTreeRepository(t)
	writeTreeFile(t, repository, "go.mod", []byte("module example.com/validation-tree\n\ngo 1.25.0\n"))
	writeTreeFile(t, repository, "main.go", []byte("package validationtree\n"))
	commit := commitCandidateTree(t, repository)
	gitPath, err := exec.LookPath("git")
	if err != nil {
		t.Fatal(err)
	}
	bin := filepath.Join(t.TempDir(), "bin")
	if err := os.MkdirAll(bin, 0o755); err != nil {
		t.Fatal(err)
	}
	logPath := filepath.Join(t.TempDir(), "tree-reads")
	wrapper := "#!/bin/sh\nREAL_GIT='" + gitPath + "'\nLOG='" + logPath + "'\nfor ARG in \"$@\"; do [ \"$ARG\" = ls-tree ] && echo read >> \"$LOG\"; done\nexec \"$REAL_GIT\" \"$@\"\n"
	if err := os.WriteFile(filepath.Join(bin, "git"), []byte(wrapper), 0o755); err != nil {
		t.Fatal(err)
	}
	t.Setenv("PATH", bin+string(os.PathListSeparator)+os.Getenv("PATH"))

	if err := Run(context.Background(), Request{RepositoryDir: repository, Commit: commit}); err != nil {
		t.Fatalf("metadata-only Run(): %v", err)
	}
	if _, err := os.Stat(logPath); !errors.Is(err, os.ErrNotExist) {
		t.Fatalf("default-only request constructed file inputs: stat error=%v", err)
	}

	err = Run(context.Background(), Request{
		RepositoryDir: repository,
		Commit:        commit,
		Settings:      Settings{SharedFiles: []string{"missing.txt"}},
	})
	var failure *Failure
	if !errors.As(err, &failure) || failure.Check != SharedFiles || len(failure.Findings) != 1 || failure.Findings[0].Path != "missing.txt" {
		t.Fatalf("explicit missing shared file Run() error = %#v", err)
	}
	if data, err := os.ReadFile(logPath); err != nil || len(data) == 0 {
		t.Fatalf("explicit shared-file request did not construct committed file inputs: %q, %v", data, err)
	}
}

func inputPaths(tree *CandidateTree) []string {
	entries := tree.InputEntries()
	paths := make([]string, 0, len(entries))
	for _, entry := range entries {
		paths = append(paths, entry.Path)
	}
	return paths
}

func TestReadFileReturnsOwnedBytesAndCachesOnlySymlinkTargets(t *testing.T) {
	repository := newTreeRepository(t)
	writeTreeFile(t, repository, "source.txt", []byte("committed content"))
	if err := os.Symlink("source.txt", filepath.Join(repository, "alias.txt")); err != nil {
		t.Fatal(err)
	}
	commit := commitCandidateTree(t, repository)
	tree, err := ReadCandidateTree(context.Background(), repository, commit)
	if err != nil {
		t.Fatal(err)
	}
	cleanupCandidateTree(t, tree)

	first, err := tree.ReadFile(context.Background(), "source.txt")
	if err != nil {
		t.Fatal(err)
	}
	first[0] = 'X'
	second, err := tree.ReadFile(context.Background(), "source.txt")
	if err != nil {
		t.Fatal(err)
	}
	if string(second) != "committed content" {
		t.Fatalf("second regular-file read = %q, want committed content", second)
	}
	if &first[0] == &second[0] {
		t.Fatal("regular-file reads share a backing byte slice")
	}

	linkFirst, err := tree.ReadFile(context.Background(), "alias.txt")
	if err != nil {
		t.Fatal(err)
	}
	linkFirst[0] = 'X'
	linkSecond, err := tree.ReadFile(context.Background(), "alias.txt")
	if err != nil {
		t.Fatal(err)
	}
	if string(linkSecond) != "source.txt" {
		t.Fatalf("second symlink read = %q, want source.txt", linkSecond)
	}
	if len(tree.symlinkTargets) != 1 {
		t.Fatalf("cached symlink target count = %d, want 1", len(tree.symlinkTargets))
	}
	destination, err := tree.ResolveDestination(context.Background(), "README.md", "alias.txt")
	if err != nil || destination.Kind != DestinationEntry || destination.Path != "source.txt" {
		t.Fatalf("ResolveDestination() = %#v, %v; want source.txt entry", destination, err)
	}
}

func cleanupCandidateTree(tb testing.TB, tree *CandidateTree) {
	tb.Helper()
	tb.Cleanup(func() { _ = tree.Close() })
}

func TestReadCandidateTreePreservesGitProcessError(t *testing.T) {
	repository := newTreeRepository(t)
	_, err := ReadCandidateTree(context.Background(), repository, strings.Repeat("f", 40))
	var exitErr *exec.ExitError
	if !errors.As(err, &exitErr) {
		t.Fatalf("ReadCandidateTree() error = %v, want Git process error preserved", err)
	}
}

type gitTreeEntry struct {
	mode    string
	kind    string
	size    int64
	hasSize bool
}

func newTreeRepository(t testing.TB) string {
	t.Helper()
	repository := t.TempDir()
	gitTree(t, repository, "init", "-b", "main")
	gitTree(t, repository, "config", "user.name", "ReleaseKit Test")
	gitTree(t, repository, "config", "user.email", "releasekit@example.invalid")
	return repository
}

func writeTreeFile(t testing.TB, repository, name string, content []byte) {
	t.Helper()
	path := filepath.Join(repository, filepath.FromSlash(name))
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(path, content, 0o644); err != nil {
		t.Fatal(err)
	}
}

func gitTree(t testing.TB, repository string, args ...string) string {
	t.Helper()
	command := exec.Command("git", args...)
	command.Dir = repository
	output, err := command.CombinedOutput()
	if err != nil {
		t.Fatalf("git %s: %v\n%s", strings.Join(args, " "), err, output)
	}
	return string(output)
}