package archive

import (
	"os"
	"path/filepath"
	"sort"
	"testing"
)

func mkTransmittal(t *testing.T, fsRoot, folderName string, files ...string) {
	t.Helper()
	dir := filepath.Join(fsRoot, folderName)
	if err := os.MkdirAll(dir, 0o755); err != nil {
		t.Fatalf("mkdir %s: %v", dir, err)
	}
	for _, f := range files {
		path := filepath.Join(dir, f)
		if err := os.WriteFile(path, []byte("x"), 0o644); err != nil {
			t.Fatalf("write %s: %v", path, err)
		}
	}
}

func TestCompareRevisions_DraftOrdering(t *testing.T) {
	cases := []struct {
		a, b string
		want int // sign only
	}{
		{"~A", "A", -1},
		{"~A", "~B", -1},
		{"A", "B", -1},
		{"~A", "~A", 0},
		{"A", "~A", 1},
	}
	for _, c := range cases {
		got := compareRevisions(c.a, c.b)
		var sign int
		if got < 0 {
			sign = -1
		} else if got > 0 {
			sign = 1
		}
		if sign != c.want {
			t.Errorf("compareRevisions(%q, %q) sign = %d, want %d", c.a, c.b, sign, c.want)
		}
	}
}

func TestIndexAndResolve_DraftOnly(t *testing.T) {
	root := t.TempDir()
	mkTransmittal(t, root, "2025-01-01_T1 (IFR) - Title",
		"123_~A (IFR) - Title.pdf",
	)

	idx, err := BuildIndex(root)
	if err != nil {
		t.Fatalf("BuildIndex: %v", err)
	}

	te, ok := idx.ByTracking["123"]
	if !ok {
		t.Fatalf("tracking 123 not indexed")
	}
	if te.HighestBaseRev != "~A" {
		t.Errorf("HighestBaseRev = %q, want ~A", te.HighestBaseRev)
	}

	if _, ok := Resolve(idx, "123.html"); !ok {
		t.Errorf("Resolve(123.html) failed")
	}
	if _, ok := Resolve(idx, "123_~A.html"); !ok {
		t.Errorf("Resolve(123_~A.html) failed")
	}
}

func TestIndexAndResolve_DraftWithModifier(t *testing.T) {
	root := t.TempDir()
	mkTransmittal(t, root, "2025-01-01_T1 (IFR) - Title",
		"123_~A (IFR) - Title.pdf",
	)
	mkTransmittal(t, root, "2025-02-01_T2 (RTN) - Comments",
		"123_~A+C1 (RTN) - Comments.pdf",
	)

	idx, _ := BuildIndex(root)
	if _, ok := Resolve(idx, "123_~A+C1.html"); !ok {
		t.Errorf("Resolve(123_~A+C1.html) failed")
	}
}

// "First chronologically found version of the latest rev": when the same rev
// appears in two transmittals, the earlier date's copy wins.
func TestRecordFile_FirstChronologicalWins(t *testing.T) {
	root := t.TempDir()
	mkTransmittal(t, root, "2025-03-01_Late (IFR) - Title",
		"123_A (IFR) - Title.pdf",
	)
	mkTransmittal(t, root, "2025-01-01_Early (IFR) - Title",
		"123_A (IFR) - Title.pdf",
	)

	idx, _ := BuildIndex(root)
	target, ok := Resolve(idx, "123_A.html")
	if !ok {
		t.Fatalf("Resolve(123_A.html) failed")
	}
	if !contains(target, "2025-01-01_Early") {
		t.Errorf("got %q, want path under 2025-01-01_Early/", target)
	}
}

// AllEntries: every (tracking) gets <tracking>.html (highest) AND a
// <tracking>_<rev>.html for every base revision present.
func TestAllEntries_PerRevisionSurfaced(t *testing.T) {
	root := t.TempDir()
	mkTransmittal(t, root, "2025-01-01_T1 (IFR) - Title",
		"123_~A (IFR) - Title.pdf",
	)
	mkTransmittal(t, root, "2025-03-01_T3 (IFC) - Title",
		"123_A (IFC) - Title.pdf",
		"456_0 (IFR) - Other.pdf",
	)

	idx, _ := BuildIndex(root)
	entries := idx.AllEntries()

	got := make(map[string]string, len(entries))
	for _, e := range entries {
		got[e.URLName] = e.TargetPath
	}

	// Highest-rev shortcut + each per-rev redirect should be present.
	wantNames := []string{
		"123.html",    // highest of 123 → A
		"123_A.html",  // explicit A
		"123_~A.html", // explicit draft
		"456.html",    // highest of 456 → 0
		"456_0.html",  // explicit 0
	}
	for _, n := range wantNames {
		if _, ok := got[n]; !ok {
			t.Errorf("missing entry %q; got %v", n, sortedKeys(got))
		}
	}

	// 123.html should resolve to the same path as 123_A.html (both point to
	// the highest-rev's first-chronological copy).
	if got["123.html"] != got["123_A.html"] {
		t.Errorf("123.html (%q) != 123_A.html (%q); should both resolve to highest",
			got["123.html"], got["123_A.html"])
	}

	// Sort: <tracking>.html sorts before <tracking>_*.html (because '.'<'_').
	for i := 1; i < len(entries); i++ {
		if entries[i-1].URLName > entries[i].URLName {
			t.Errorf("AllEntries not sorted: %q before %q", entries[i-1].URLName, entries[i].URLName)
		}
	}
}

// Modifier-only files (no base) don't get a <tracking>.html or
// <tracking>_<rev>.html entry — the redirect would have nowhere to go since
// re.BasePath is empty. They remain reachable via <tracking>_<rev>+<mod>.html
// through the resolver but are not surfaced in the listing.
func TestAllEntries_ModifierOnlyNoBaseSkipped(t *testing.T) {
	root := t.TempDir()
	mkTransmittal(t, root, "2025-02-01_T2 (RTN) - Comments",
		"123_~A+C1 (RTN) - Comments.pdf",
	)

	idx, _ := BuildIndex(root)
	for _, e := range idx.AllEntries() {
		if e.URLName == "123.html" || e.URLName == "123_~A.html" {
			t.Errorf("unexpected entry %q (no base file exists)", e.URLName)
		}
	}
}

func contains(s, sub string) bool {
	for i := 0; i+len(sub) <= len(s); i++ {
		if s[i:i+len(sub)] == sub {
			return true
		}
	}
	return false
}

func sortedKeys(m map[string]string) []string {
	out := make([]string, 0, len(m))
	for k := range m {
		out = append(out, k)
	}
	sort.Strings(out)
	return out
}