package validation

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

func TestCheckMarkdownLinksResolvesCommittedDestinationsAndFragments(t *testing.T) {
	guide := []byte("" +
		"# Start\n" +
		"[target](target.md?view=1#TARGET)\n" +
		"[same](#START)\n" +
		"[url heading](autolinks.md#httpsexampleinvalid)\n" +
		"[email heading](autolinks.md#maintainerexampleinvalid)\n" +
		"[top](#)\n" +
		"[directory](assets/?view=1)\n" +
		"[binary](image.bin#not-an-anchor)\n" +
		"[encoded](docs/a%20b.md#CAF%C3%89)\n" +
		"[query](target.md?view=%ZZ)\n" +
		"[external](https://example.invalid/%ZZ#also%ZZ)\n" +
		"[protocol-relative](//example.invalid/file.md)\n")
	repository, tree := committedMarkdownTree(t, map[string][]byte{
		"guide.md":        guide,
		"target.md":       []byte("# Target\n"),
		"autolinks.md":    []byte("# <https://example.invalid>\n# <maintainer@example.invalid>\n"),
		"docs/a b.md":     []byte("# Café\n"),
		"assets/file.md":  []byte("# Asset\n"),
		"nested/guide.md": []byte("# Nested\n[same](#NESTED)\n[query](?view=1#nested)\n"),
		"image.bin":       []byte{0, 1, 2},
	})

	if err := checkMarkdownLinks(context.Background(), tree, false, nil); err != nil {
		t.Fatalf("checkMarkdownLinks() error = %v", err)
	}
	if got := readCommitted(t, tree, "guide.md"); !bytes.Equal(got, guide) {
		t.Fatal("checker changed committed Markdown bytes")
	}
	if got, err := os.ReadFile(filepath.Join(repository, "guide.md")); err != nil || !bytes.Equal(got, guide) {
		t.Fatalf("worktree Markdown changed: got %q, err %v", got, err)
	}
}

func TestCheckMarkdownLinksTreatsImageLabelsAsAlternativeText(t *testing.T) {
	_, tree := committedMarkdownTree(t, map[string][]byte{
		"guide.md": []byte("" +
			"![![inner](missing.png)](image.png)\n" +
			"![[label](missing.md)](image.png)\n" +
			"![[anchor](target.md#absent)](image.png)\n" +
			"![[outside](../outside.md)](image.png)\n" +
			"[![logo](image.png)](target.md#present)\n" +
			"[![missing](absent.png)](absent.md)\n"),
		"image.png": []byte("image"),
		"target.md": []byte("# Present\n"),
	})
	for _, enforceBoundary := range []bool{false, true} {
		t.Run(fmt.Sprintf("boundary=%t", enforceBoundary), func(t *testing.T) {
			err := checkMarkdownLinks(context.Background(), tree, enforceBoundary, nil)
			var failure *Failure
			if !errors.As(err, &failure) || failure.Check != MarkdownLinks || len(failure.Findings) != 2 {
				t.Fatalf("error = %v, want only the missing linked-image source and link target", err)
			}
			want := map[string]bool{"absent.png": true, "absent.md": true}
			for _, finding := range failure.Findings {
				if !want[finding.Target] {
					t.Errorf("unexpected destination finding: %#v", finding)
				}
				delete(want, finding.Target)
			}
			if len(want) != 0 {
				t.Errorf("missing findings for real destinations: %v", want)
			}
		})
	}
}

func TestCheckMarkdownLinksReportsMissingPathsAnchorsAndCycles(t *testing.T) {
	_, tree := committedMarkdownTree(t, map[string][]byte{
		"guide.md": []byte("" +
			"[missing](absent.md)\n" +
			"[anchor](target.md#missing)\n" +
			"[cycle](cycle-a)\n"),
		"target.md": []byte("# Present\n"),
	})
	repository := tree.repositoryDir
	if err := os.Symlink("cycle-b", filepath.Join(repository, "cycle-a")); err != nil {
		t.Fatal(err)
	}
	if err := os.Symlink("cycle-a", filepath.Join(repository, "cycle-b")); err != nil {
		t.Fatal(err)
	}
	gitTree(t, repository, "add", "cycle-a", "cycle-b")
	gitTree(t, repository, "commit", "-m", "add markdown link cycle")
	tree = candidateTreeAtHead(t, repository)

	err := checkMarkdownLinks(context.Background(), tree, false, nil)
	var failure *Failure
	if !errors.As(err, &failure) {
		t.Fatalf("checkMarkdownLinks() error = %v, want validation Failure", err)
	}
	if failure.Check != MarkdownLinks {
		t.Fatalf("failure check = %q, want %q", failure.Check, MarkdownLinks)
	}
	if len(failure.Findings) != 3 {
		t.Fatalf("findings = %#v, want missing path, anchor, and cycle", failure.Findings)
	}
	want := map[string]string{
		"absent.md":         "destination does not exist",
		"target.md#missing": "heading anchor does not exist",
		"cycle-a":           "destination contains a symlink cycle",
	}
	for _, finding := range failure.Findings {
		if finding.Path != "guide.md" || finding.Line < 1 || finding.Column < 1 {
			t.Errorf("finding lacks source location: %#v", finding)
		}
		if want[finding.Target] != finding.Message {
			t.Errorf("finding = %#v", finding)
		}
		delete(want, finding.Target)
	}
	if len(want) != 0 {
		t.Fatalf("missing expected findings for %#v", want)
	}
}

func TestCheckMarkdownLinksUsesResolvedMarkdownIdentity(t *testing.T) {
	repository, _ := committedMarkdownTree(t, map[string][]byte{
		"guide.md":  []byte("[valid](alias.md#present)\n[missing](alias.md#missing)\n"),
		"target.md": []byte("# Present\n"),
	})
	if err := os.Symlink("target.md", filepath.Join(repository, "alias.md")); err != nil {
		t.Fatal(err)
	}
	gitTree(t, repository, "add", "alias.md")
	gitTree(t, repository, "commit", "-m", "add Markdown alias")
	tree := candidateTreeAtHead(t, repository)

	err := checkMarkdownLinks(context.Background(), tree, false, nil)
	var failure *Failure
	if !errors.As(err, &failure) || failure.Check != MarkdownLinks || len(failure.Findings) != 1 {
		t.Fatalf("resolved alias error = %v, want one missing-anchor finding", err)
	}
	if finding := failure.Findings[0]; finding.Path != "guide.md" || finding.Target != "alias.md#missing" || finding.Message != "heading anchor does not exist" {
		t.Fatalf("resolved alias finding = %#v", finding)
	}
}

func TestCheckMarkdownLinksReportsBoundaryAndSubmoduleObservations(t *testing.T) {
	repository, tree := committedMarkdownTree(t, map[string][]byte{
		"guide.md": []byte("[outside](../../outside.md)\n[submodule](deps/module/README.md)\n"),
	})
	commit := strings.TrimSpace(gitTree(t, repository, "rev-parse", "HEAD"))
	gitTree(t, repository, "update-index", "--add", "--cacheinfo", fmt.Sprintf("160000,%s,deps/module", commit))
	gitTree(t, repository, "commit", "-m", "add submodule entry")
	tree = candidateTreeAtHead(t, repository)

	var observed bytes.Buffer
	if err := checkMarkdownLinks(context.Background(), tree, false, &observed); err != nil {
		t.Fatalf("checkMarkdownLinks() error = %v", err)
	}
	if got := observed.String(); !strings.Contains(got, "outside the checkout") || !strings.Contains(got, "uninspected submodule content") || strings.Count(got, "out of scope") != 2 {
		t.Fatalf("out-of-scope observations = %q", got)
	}

	observed.Reset()
	err := checkMarkdownLinks(context.Background(), tree, true, &observed)
	var failure *Failure
	if !errors.As(err, &failure) || failure.Check != MarkdownLinks || len(failure.Findings) != 1 {
		t.Fatalf("enforced boundary error = %v, want one Markdown finding", err)
	}
	if finding := failure.Findings[0]; finding.Target != "../../outside.md" || finding.Message != "destination is outside the checkout" {
		t.Fatalf("boundary finding = %#v", finding)
	}
	if got := observed.String(); !strings.Contains(got, "uninspected submodule content") || strings.Contains(got, "outside the checkout") {
		t.Fatalf("enforced observations = %q", got)
	}
}

func TestCheckMarkdownLinksPreservesResolverCauseAndCancellation(t *testing.T) {
	repository, tree := committedMarkdownTree(t, map[string][]byte{
		"guide.md": []byte("[target](broken.md)\n"),
	})
	if err := os.Symlink("target.md", filepath.Join(repository, "broken.md")); err != nil {
		t.Fatal(err)
	}
	gitTree(t, repository, "add", "broken.md")
	gitTree(t, repository, "commit", "-m", "add Markdown symlink")
	tree = candidateTreeAtHead(t, repository)
	index := tree.byPath["broken.md"]
	tree.entries[index].ObjectID = strings.Repeat("0", 40)

	err := checkMarkdownLinks(context.Background(), tree, false, nil)
	var failure *Failure
	if !errors.As(err, &failure) || failure.Check != MarkdownLinks || failure.Cause == nil {
		t.Fatalf("resolver inspection error = %v, want Markdown failure with cause", err)
	}
	if len(failure.Findings) != 1 || failure.Findings[0].Path != "guide.md" || failure.Findings[0].Line != 1 || failure.Findings[0].Target != "broken.md" {
		t.Fatalf("resolver inspection finding = %#v", failure.Findings)
	}

	ctx, cancel := context.WithCancel(context.Background())
	cancel()
	err = checkMarkdownLinks(ctx, tree, false, nil)
	if !errors.As(err, &failure) || failure.Check != MarkdownLinks || !errors.Is(err, context.Canceled) {
		t.Fatalf("canceled Markdown check error = %v, want preserved cancellation", err)
	}
}

func TestCheckMarkdownLinksPreservesAnchorReadCause(t *testing.T) {
	_, tree := committedMarkdownTree(t, map[string][]byte{
		"guide.md":  []byte("[target](target.md#present)\n"),
		"target.md": []byte("# Present\n"),
	})
	tree.entries[tree.byPath["target.md"]].ObjectID = strings.Repeat("0", 40)

	err := checkMarkdownLinks(context.Background(), tree, false, nil)
	var failure *Failure
	if !errors.As(err, &failure) || failure.Check != MarkdownLinks || failure.Cause == nil {
		t.Fatalf("anchor inspection error = %v, want Markdown failure with cause", err)
	}
	if len(failure.Findings) != 1 || failure.Findings[0].Path != "guide.md" || failure.Findings[0].Target != "target.md#present" || failure.Findings[0].Message != "could not inspect destination anchor" {
		t.Fatalf("anchor inspection finding = %#v", failure.Findings)
	}
}

func TestRunSelectsMarkdownWithCombinedGoChecksAndReportsOutOfScopeLinks(t *testing.T) {
	repository, _ := committedMarkdownTree(t, map[string][]byte{
		"guide.md": []byte("[outside](../../outside.md)\n"),
	})
	commit := strings.TrimSpace(gitTree(t, repository, "rev-parse", "HEAD"))
	goLog := installGoShim(t, "", false)
	var output bytes.Buffer
	err := Run(context.Background(), Request{
		RepositoryDir: repository,
		Commit:        commit,
		Output:        &output,
		Settings: Settings{
			Race:           true,
			FullVet:        true,
			CompileTargets: []Target{{OS: "linux", Arch: "amd64"}},
			Markdown:       &MarkdownSettings{},
		},
	})
	if err != nil {
		t.Fatalf("Run() error = %v, want out-of-scope observation to succeed", err)
	}
	if got := output.String(); !strings.Contains(got, "outside the checkout") || !strings.Contains(got, "out of scope") {
		t.Fatalf("Run() output = %q, want outside-checkout observation", got)
	}
	commands := readGoShimLog(t, goLog)
	var testCommands []string
	var validationCommands []string
	for _, command := range commands {
		if strings.HasPrefix(command, "test ") {
			testCommands = append(testCommands, command)
		}
		if strings.HasPrefix(command, "test ") || strings.HasPrefix(command, "vet ") || strings.HasPrefix(command, "build ") {
			validationCommands = append(validationCommands, command)
		}
	}
	if len(testCommands) != 1 || !strings.Contains(testCommands[0], "-race") || !strings.Contains(testCommands[0], "-vet=off") {
		t.Fatalf("Go test commands = %#v, want one race-enabled suite with test-time vet disabled", testCommands)
	}
	if len(validationCommands) != 3 || !strings.HasPrefix(validationCommands[0], "test ") || !strings.HasPrefix(validationCommands[1], "vet ") || !strings.HasPrefix(validationCommands[2], "build ") {
		t.Fatalf("Go validation commands = %#v, want test, full vet, and target compilation before Markdown", validationCommands)
	}
}

func committedMarkdownTree(t *testing.T, files map[string][]byte) (string, *CandidateTree) {
	t.Helper()
	repository := newTreeRepository(t)
	for name, content := range files {
		writeTreeFile(t, repository, name, content)
	}
	gitTree(t, repository, "add", "--", ".")
	gitTree(t, repository, "commit", "-m", "add Markdown fixture")
	return repository, candidateTreeAtHead(t, repository)
}

func candidateTreeAtHead(t *testing.T, repository string) *CandidateTree {
	t.Helper()
	commit := strings.TrimSpace(gitTree(t, repository, "rev-parse", "HEAD"))
	tree, err := ReadCandidateTree(context.Background(), repository, commit)
	if err != nil {
		t.Fatal(err)
	}
	cleanupCandidateTree(t, tree)
	return tree
}

func readCommitted(t *testing.T, tree *CandidateTree, name string) []byte {
	t.Helper()
	contents, err := tree.ReadFile(context.Background(), name)
	if err != nil {
		t.Fatal(err)
	}
	return contents
}