package upload

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

	"booklib/internal/ports"
)

func newU(t *testing.T) *U {
	t.Helper()
	dir := t.TempDir()
	resolved, err := filepath.EvalSymlinks(dir)
	if err != nil {
		t.Fatal(err)
	}
	return New(resolved, 1) // 1MB cap, mirrors handler test cfg
}

func mustInit(t *testing.T, u *U, libID int64, name string, size, chunk int64) string {
	t.Helper()
	uid, err := u.Init(context.Background(), libID, name, size, chunk)
	if err != nil {
		t.Fatalf("Init(%q): %v", name, err)
	}
	return uid
}

func TestUploadIDForDeterministic(t *testing.T) {
	a := uploadIDFor(1, "x.cbz", 100, 50)
	b := uploadIDFor(1, "x.cbz", 100, 50)
	c := uploadIDFor(2, "x.cbz", 100, 50)
	if a != b {
		t.Fatalf("same fingerprint must yield same uid: %s vs %s", a, b)
	}
	if a == c {
		t.Fatal("different libID must yield different uid")
	}
	if !validUploadID(a) || validUploadID("zzz") || validUploadID(strings.Repeat("a", 31)) {
		t.Fatal("validUploadID broken")
	}
}

func TestInitValidation(t *testing.T) {
	u := newU(t)
	ctx := context.Background()
	if _, err := u.Init(ctx, 1, "", 100, 0); !errors.Is(err, ErrBadName) {
		t.Fatalf("empty name: want ErrBadName got %v", err)
	}
	if _, err := u.Init(ctx, 1, "virus.exe", 100, 0); !errors.Is(err, ErrBadFormat) {
		t.Fatalf("bad ext: want ErrBadFormat got %v", err)
	}
	if _, err := u.Init(ctx, 1, "ok.cbz", 0, 0); !errors.Is(err, ErrBadSize) {
		t.Fatalf("zero size: want ErrBadSize got %v", err)
	}
	if _, err := u.Init(ctx, 1, "big.cbz", 2<<20, 0); !errors.Is(err, ports.ErrTooLarge) {
		t.Fatalf("oversize: want ErrTooLarge got %v", err)
	}
	if _, err := u.Init(ctx, 1, "ok.cbz", 100, 40<<20); !errors.Is(err, ErrBadChunk) {
		t.Fatalf("huge chunk: want ErrBadChunk got %v", err)
	}
	// 默认 chunk 生效且 uid 稳定
	uid := mustInit(t, u, 1, "ok.cbz", 100, 0)
	if uid != uploadIDFor(1, "ok.cbz", 100, defaultChunk) {
		t.Fatal("chunkSize=0 must default to defaultChunk in fingerprint")
	}
	// SafeName 清洗:path 形式取 base
	if uid2 := mustInit(t, u, 1, `C:\dir\book.cbz`, 100, 0); uid2 != uploadIDFor(1, "book.cbz", 100, defaultChunk) {
		t.Fatalf("windows path must be sanitized to base name, got uid %s", uid2)
	}
}

func TestInitResumeAndRestart(t *testing.T) {
	u := newU(t)
	ctx := context.Background()
	uid := mustInit(t, u, 1, "r.cbz", 900000, 400000)
	if err := u.PutPart(ctx, uid, 0, bytes.NewReader(bytes.Repeat([]byte("x"), 400000)), 0); err != nil {
		t.Fatalf("PutPart: %v", err)
	}
	// 同指纹 re-init → 复用会话,分片保留
	uid2, err := u.Init(ctx, 1, "r.cbz", 900000, 400000)
	if err != nil || uid2 != uid {
		t.Fatalf("resume: want same uid, got %s err=%v", uid2, err)
	}
	recv, err := u.Status(ctx, uid)
	if err != nil || len(recv) != 1 || recv[0] != 0 {
		t.Fatalf("resume must keep parts: %v err=%v", recv, err)
	}
	// 同指纹位但内容不同(size 变)→ 新会话,旧目录被换掉是安全的(uid 不同)
	uid3 := mustInit(t, u, 1, "r.cbz", 800000, 400000)
	if uid3 == uid {
		t.Fatal("different size must yield different uid")
	}
}

func TestPutPartErrors(t *testing.T) {
	u := newU(t)
	ctx := context.Background()
	uid := mustInit(t, u, 1, "p.cbz", 1000, 400)
	if err := u.PutPart(ctx, uid, 9, bytes.NewReader(bytes.Repeat([]byte("y"), 400)), 0); !errors.Is(err, ErrBadIndex) {
		t.Fatalf("index oob: want ErrBadIndex got %v", err)
	}
	if err := u.PutPart(ctx, uid, -1, bytes.NewReader(nil), 0); !errors.Is(err, ErrBadIndex) {
		t.Fatalf("negative index: want ErrBadIndex got %v", err)
	}
	// 超期望体积 → ErrPartTooBig
	if err := u.PutPart(ctx, uid, 0, bytes.NewReader(bytes.Repeat([]byte("y"), 500)), 0); !errors.Is(err, ErrPartTooBig) {
		t.Fatalf("oversize part: want ErrPartTooBig got %v", err)
	}
	// 短读 → ErrPartSizeMismatch
	if err := u.PutPart(ctx, uid, 0, bytes.NewReader(bytes.Repeat([]byte("y"), 300)), 0); !errors.Is(err, ErrPartSizeMismatch) {
		t.Fatalf("short part: want ErrPartSizeMismatch got %v", err)
	}
	// 失败不留 parts/B4: 截断分片不被 Status 报告为已接收
	recv, err := u.Status(ctx, uid)
	if err != nil || len(recv) != 0 {
		t.Fatalf("failed parts must not be received: %v err=%v", recv, err)
	}
	// 未知/非法 uid
	if _, err := u.Status(ctx, "deadbeefdeadbeefdeadbeefdeadbeef"); !errors.Is(err, ports.ErrNotFound) {
		t.Fatalf("unknown uid: want ErrNotFound got %v", err)
	}
	if _, err := u.Status(ctx, "zzz"); !errors.Is(err, ErrBadUploadID) {
		t.Fatalf("bad uid: want ErrBadUploadID got %v", err)
	}
}

func TestCompleteHappyPathAndCleanup(t *testing.T) {
	u := newU(t)
	ctx := context.Background()
	root := filepath.Join(u.booksDir, "lib")
	if err := os.MkdirAll(root, 0o755); err != nil {
		t.Fatal(err)
	}
	content := bytes.Repeat([]byte("調教開關第二季!"), 300) // ~6.3KB multibyte
	size := int64(len(content))
	const chunk = int64(2000)
	uid := mustInit(t, u, 7, "調教開關：第二季.zip", size, chunk)
	n := int((size + chunk - 1) / chunk)
	// 乱序上传:索引顺序 1,2,...,n-1,0 —— 覆盖所有分片且非递增
	for step := 1; step <= n; step++ {
		idx := int64(step % n)
		lo := idx * chunk
		hi := min(lo+chunk, size)
		if err := u.PutPart(ctx, uid, idx, bytes.NewReader(content[lo:hi]), 0); err != nil {
			t.Fatalf("PutPart %d: %v", idx, err)
		}
	}
	// 缺片 → ErrIncomplete(先删一片验证)
	part0 := filepath.Join(u.uploadDir(uid), "parts", "0")
	saved, _ := os.ReadFile(part0)
	os.Remove(part0)
	if _, err := u.Complete(ctx, uid, root); !errors.Is(err, ports.ErrIncomplete) {
		t.Fatalf("missing part: want ErrIncomplete got %v", err)
	}
	os.WriteFile(part0, saved, 0o644)

	rel, err := u.Complete(ctx, uid, root)
	if err != nil {
		t.Fatalf("Complete: %v", err)
	}
	if rel != "調教開關：第二季.zip" {
		t.Fatalf("rel path: %q", rel)
	}
	got, err := os.ReadFile(filepath.Join(root, rel))
	if err != nil || !bytes.Equal(got, content) {
		t.Fatalf("assembled content wrong: err=%v", err)
	}
	if _, err := os.Stat(u.uploadDir(uid)); !os.IsNotExist(err) {
		t.Fatal("session dir must be removed after complete")
	}
}

func TestCompleteUniquePathCollision(t *testing.T) {
	u := newU(t)
	ctx := context.Background()
	root := filepath.Join(u.booksDir, "lib")
	os.MkdirAll(root, 0o755)
	os.WriteFile(filepath.Join(root, "dup.cbz"), []byte("existing"), 0o644)
	uid := mustInit(t, u, 1, "dup.cbz", 4, 4)
	if err := u.PutPart(ctx, uid, 0, bytes.NewReader([]byte("new!")), 0); err != nil {
		t.Fatal(err)
	}
	rel, err := u.Complete(ctx, uid, root)
	if err != nil {
		t.Fatalf("Complete: %v", err)
	}
	if rel != "dup (1).cbz" {
		t.Fatalf("collision must add suffix, got %q", rel)
	}
}

func TestUniquePathTraversalRejected(t *testing.T) {
	u := newU(t)
	root := filepath.Join(u.booksDir, "lib")
	if _, err := u.UniquePath(root, "../escape.cbz"); !errors.Is(err, os.ErrInvalid) {
		t.Fatalf("traversal: want os.ErrInvalid got %v", err)
	}
	p, err := u.UniquePath(root, "ok.cbz")
	if err != nil || p != filepath.Join(root, "ok.cbz") {
		t.Fatalf("valid name: %q %v", p, err)
	}
}

func TestSweepRemovesOnlyExpired(t *testing.T) {
	u := newU(t)
	ctx := context.Background()
	fresh := mustInit(t, u, 1, "fresh.cbz", 10, 10)
	stale := mustInit(t, u, 1, "stale.cbz", 10, 10)
	// 把 stale 会话 mtime 拨到 TTL 之前
	old := time.Now().Add(-uploadSessTTL - time.Hour)
	dir := u.uploadDir(stale)
	if err := os.Chtimes(filepath.Join(dir, "meta.json"), old, old); err != nil {
		t.Fatal(err)
	}
	if err := os.Chtimes(dir, old, old); err != nil {
		t.Fatal(err)
	}
	if err := u.Sweep(ctx); err != nil {
		t.Fatalf("Sweep: %v", err)
	}
	if _, err := os.Stat(dir); !os.IsNotExist(err) {
		t.Fatal("stale session must be swept")
	}
	if _, err := os.Stat(u.uploadDir(fresh)); err != nil {
		t.Fatalf("fresh session must survive: %v", err)
	}
	// 空目录/不存在 base 都不报错
	os.RemoveAll(filepath.Join(u.booksDir, uploadSessionIn))
	if err := u.Sweep(ctx); err != nil {
		t.Fatalf("Sweep on missing base: %v", err)
	}
}

func TestLibraryID(t *testing.T) {
	u := newU(t)
	ctx := context.Background()
	uid := mustInit(t, u, 42, "lib.cbz", 10, 10)
	id, err := u.LibraryID(ctx, uid)
	if err != nil || id != 42 {
		t.Fatalf("LibraryID: %d %v", id, err)
	}
	if _, err := u.LibraryID(ctx, "deadbeefdeadbeefdeadbeefdeadbeef"); !errors.Is(err, ports.ErrNotFound) {
		t.Fatalf("unknown uid: want ErrNotFound got %v", err)
	}
}