package handler

import (
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"net/url"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"codeberg.org/VARASYS/ZDDC/zddc/internal/zddc"
)

func mustNoErr(t *testing.T, err error) {
	t.Helper()
	if err != nil {
		t.Fatal(err)
	}
}

func countBlobs(t *testing.T, histDir string) int {
	t.Helper()
	ents, err := os.ReadDir(histDir)
	if err != nil {
		t.Fatalf("read history dir: %v", err)
	}
	n := 0
	for _, e := range ents {
		if strings.HasSuffix(e.Name(), ".md") {
			n++
		}
	}
	return n
}

func TestWriteTextWithHistory_CreateUpdateDedupRestore(t *testing.T) {
	dir := t.TempDir()
	abs := filepath.Join(dir, "notes.md")
	histDir := filepath.Join(dir, ".history", "notes")
	sha1 := fileETag([]byte("v1"))
	sha2 := fileETag([]byte("v2"))

	// ── create ──
	mustNoErr(t, WriteTextWithHistory(abs, []byte("v1"), "alice@x.com"))
	if b, _ := os.ReadFile(abs); string(b) != "v1" {
		t.Fatalf("live = %q, want v1", b)
	}
	entries, err := ListMdHistory(abs)
	mustNoErr(t, err)
	if len(entries) != 1 {
		t.Fatalf("after create: want 1 entry, got %d", len(entries))
	}
	if entries[0].By != "alice@x.com" {
		t.Errorf("by = %q, want alice@x.com", entries[0].By)
	}
	if entries[0].Sha != sha1 {
		t.Errorf("sha = %q, want %q", entries[0].Sha, sha1)
	}
	if !entries[0].Current {
		t.Errorf("v1 should be current")
	}
	if _, err := os.Stat(filepath.Join(histDir, sha1+".md")); err != nil {
		t.Errorf("v1 blob missing: %v", err)
	}

	// ── update ──
	time.Sleep(2 * time.Millisecond) // distinct RFC3339Nano ts for ordering
	mustNoErr(t, WriteTextWithHistory(abs, []byte("v2"), "bob@x.com"))
	if b, _ := os.ReadFile(abs); string(b) != "v2" {
		t.Fatalf("live = %q, want v2", b)
	}
	entries, _ = ListMdHistory(abs)
	if len(entries) != 2 {
		t.Fatalf("after update: want 2 entries, got %d", len(entries))
	}
	// newest first
	if entries[0].Sha != sha2 || !entries[0].Current {
		t.Errorf("head = %+v, want v2 current", entries[0])
	}
	if entries[0].Prev != sha1 {
		t.Errorf("v2.prev = %q, want %q", entries[0].Prev, sha1)
	}
	if entries[1].Sha != sha1 || entries[1].Current {
		t.Errorf("tail = %+v, want v1 non-current", entries[1])
	}
	if entries[1].By != "alice@x.com" {
		t.Errorf("v1 author lost: %q", entries[1].By)
	}

	// ── no-op save (identical content) → dedup, no new entry ──
	mustNoErr(t, WriteTextWithHistory(abs, []byte("v2"), "bob@x.com"))
	entries, _ = ListMdHistory(abs)
	if len(entries) != 2 {
		t.Fatalf("dedup failed: want 2 entries, got %d", len(entries))
	}

	// ── restore v1 content → new log entry, blob reused ──
	time.Sleep(2 * time.Millisecond)
	mustNoErr(t, WriteTextWithHistory(abs, []byte("v1"), "carol@x.com"))
	if b, _ := os.ReadFile(abs); string(b) != "v1" {
		t.Fatalf("live = %q, want restored v1", b)
	}
	entries, _ = ListMdHistory(abs)
	if len(entries) != 3 {
		t.Fatalf("after restore: want 3 entries, got %d", len(entries))
	}
	if entries[0].Sha != sha1 || !entries[0].Current || entries[0].By != "carol@x.com" {
		t.Errorf("head = %+v, want restored v1 by carol, current", entries[0])
	}
	// Only the newest matching entry is current, even though the oldest
	// entry has the same sha.
	if entries[2].Current {
		t.Errorf("oldest v1 entry should not be current: %+v", entries[2])
	}
	// Content-addressed: only two distinct blobs (v1, v2) despite 3 saves.
	if n := countBlobs(t, histDir); n != 2 {
		t.Errorf("distinct blobs = %d, want 2", n)
	}
}

func TestWriteTextWithHistory_LazySeedPreexisting(t *testing.T) {
	dir := t.TempDir()
	abs := filepath.Join(dir, "doc.md")
	// Simulate a file that existed before history was enabled.
	mustNoErr(t, zddc.WriteAtomic(abs, []byte("legacy")))

	mustNoErr(t, WriteTextWithHistory(abs, []byte("edited"), "dave@x.com"))

	entries, err := ListMdHistory(abs)
	mustNoErr(t, err)
	if len(entries) != 2 {
		t.Fatalf("lazy-seed: want 2 entries (seeded prior + new), got %d", len(entries))
	}
	// newest = the edit; oldest = the seeded legacy version (author unknown)
	if entries[0].By != "dave@x.com" || entries[0].Sha != fileETag([]byte("edited")) {
		t.Errorf("head = %+v, want edit by dave", entries[0])
	}
	if entries[1].By != "" || entries[1].Sha != fileETag([]byte("legacy")) {
		t.Errorf("seed = %+v, want legacy with empty author", entries[1])
	}
}

func TestWriteTextWithHistory_EmptyAuthorAnonymous(t *testing.T) {
	dir := t.TempDir()
	abs := filepath.Join(dir, "x.md")
	mustNoErr(t, WriteTextWithHistory(abs, []byte("a"), ""))
	entries, _ := ListMdHistory(abs)
	if len(entries) != 1 || entries[0].By != "anonymous" {
		t.Fatalf("empty author should record anonymous, got %+v", entries)
	}
}

func TestServeTextHistory_ListAndVersion(t *testing.T) {
	dir := t.TempDir()
	abs := filepath.Join(dir, "page.md")
	mustNoErr(t, WriteTextWithHistory(abs, []byte("one"), "a@x.com"))
	time.Sleep(2 * time.Millisecond)
	mustNoErr(t, WriteTextWithHistory(abs, []byte("two"), "b@x.com"))
	sha1 := fileETag([]byte("one"))

	// ── list ──
	req := httptest.NewRequest(http.MethodGet, "/page.md?history=1", nil)
	rec := httptest.NewRecorder()
	ServeTextHistory(rec, req, abs, "1")
	if rec.Code != http.StatusOK {
		t.Fatalf("list status = %d", rec.Code)
	}
	var got []MdHistoryEntry
	if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil {
		t.Fatalf("list body not JSON: %v", err)
	}
	if len(got) != 2 || got[0].By != "b@x.com" {
		t.Fatalf("list = %+v, want 2 newest-first", got)
	}

	// ── specific version content ──
	req = httptest.NewRequest(http.MethodGet, "/page.md?history="+sha1, nil)
	rec = httptest.NewRecorder()
	ServeTextHistory(rec, req, abs, sha1)
	if rec.Code != http.StatusOK {
		t.Fatalf("version status = %d", rec.Code)
	}
	if rec.Body.String() != "one" {
		t.Errorf("version body = %q, want %q", rec.Body.String(), "one")
	}
	if ct := rec.Header().Get("Content-Type"); !strings.HasPrefix(ct, "text/markdown") {
		t.Errorf("content-type = %q", ct)
	}
}

func TestServeTextHistory_RejectsTraversalAndBadInput(t *testing.T) {
	dir := t.TempDir()
	abs := filepath.Join(dir, "p.md")
	mustNoErr(t, WriteTextWithHistory(abs, []byte("x"), "a@x.com"))
	// Drop a secret in the parent so a successful traversal would be visible.
	mustNoErr(t, zddc.WriteAtomic(filepath.Join(dir, "secret"), []byte("TOPSECRET")))

	for _, bad := range []string{"../secret", "..%2Fsecret", "abc/def", "ZZZ", "deadbeef.md"} {
		req := httptest.NewRequest(http.MethodGet, "/p.md?history="+url.QueryEscape(bad), nil)
		rec := httptest.NewRecorder()
		ServeTextHistory(rec, req, abs, bad)
		if rec.Code == http.StatusOK {
			t.Errorf("version %q unexpectedly served: body=%q", bad, rec.Body.String())
		}
		if strings.Contains(rec.Body.String(), "TOPSECRET") {
			t.Fatalf("traversal leaked secret for input %q", bad)
		}
	}

	// Non-markdown path → 404 (history not applicable).
	yamlAbs := filepath.Join(dir, "rec.yaml")
	req := httptest.NewRequest(http.MethodGet, "/rec.yaml?history=1", nil)
	rec := httptest.NewRecorder()
	ServeTextHistory(rec, req, yamlAbs, "1")
	if rec.Code != http.StatusNotFound {
		t.Errorf("non-md status = %d, want 404", rec.Code)
	}
}