package main

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"net/url"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strings"
	"sync"
	"testing"
	"time"
)

// fakeForge answers the forge's interface from maps, and records every delete.
type fakeForge struct {
	t        *testing.T
	versions map[string][]string          // package -> versions
	tags     map[string]map[string]string // package -> dist-tags
	repos    map[string]map[string]string // repository -> path -> content
	broken   map[string]bool              // repositories whose tree answers 500
	files    map[string][]int64           // package@version -> its files' sizes (default 1 MiB + 1 KiB)
	noSize   map[string]bool              // package@version whose files answer 500
	mu       sync.Mutex
	deleted  []string
	password string
}

func (f *fakeForge) serve() *Forge {
	srv := httptest.NewServer(http.HandlerFunc(f.handle))
	f.t.Cleanup(srv.Close)
	file := filepath.Join(f.t.TempDir(), "admin.secret")
	if err := os.WriteFile(file, []byte(f.password+"\n"), 0o600); err != nil {
		f.t.Fatal(err)
	}
	return &Forge{URL: srv.URL, User: "admin", PasswordFile: file, Owner: "acme"}
}

var (
	versionFiles = regexp.MustCompile(`^/api/v1/packages/acme/npm/([^/]+)/([^/]+)(/files)?$`)
	treePath     = regexp.MustCompile(`^/api/v1/repos/([^/]+)/([^/]+)/git/trees/`)
	rawPath      = regexp.MustCompile(`^/api/v1/repos/([^/]+)/([^/]+)/raw/(.+)$`)
)

func (f *fakeForge) handle(w http.ResponseWriter, r *http.Request) {
	user, pass, ok := r.BasicAuth()
	if !ok || user != "admin" || pass != f.password {
		http.Error(w, "unauthorised", http.StatusUnauthorized)
		return
	}
	p := r.URL.EscapedPath()
	q := r.URL.Query()
	page := 1
	fmt.Sscan(q.Get("page"), &page)
	switch {
	case p == "/api/v1/packages/acme" && r.Method == http.MethodGet:
		var all []map[string]any
		names := keys(f.versions)
		for _, n := range names {
			for i, v := range f.versions[n] {
				all = append(all, map[string]any{"name": n, "version": v, "type": "npm",
					"created_at": time.Date(2026, 1, 1+i, 0, 0, 0, 0, time.UTC)})
			}
		}
		writeJSON(w, pageOf(all, page, pageSize))
	case strings.HasPrefix(p, "/api/packages/acme/npm/"):
		name, _ := url.PathUnescape(strings.TrimPrefix(p, "/api/packages/acme/npm/"))
		writeJSON(w, map[string]any{"name": name, "dist-tags": f.tags[name]})
	case versionFiles.MatchString(p):
		m := versionFiles.FindStringSubmatch(p)
		name, _ := url.PathUnescape(m[1])
		version, _ := url.PathUnescape(m[2])
		if m[3] != "" {
			if f.noSize[name+"@"+version] {
				http.Error(w, "storage unavailable", http.StatusInternalServerError)
				return
			}
			sizes, has := f.files[name+"@"+version]
			if !has {
				sizes = []int64{1 << 20, 1024}
			}
			var files []map[string]any
			for i, n := range sizes {
				files = append(files, map[string]any{"id": i + 1, "size": n, "name": fmt.Sprintf("f%d", i), "md5": "x"})
			}
			writeJSON(w, files)
			return
		}
		if r.Method != http.MethodDelete {
			http.Error(w, "no", http.StatusMethodNotAllowed)
			return
		}
		f.mu.Lock()
		f.deleted = append(f.deleted, name+"@"+version)
		f.mu.Unlock()
		w.WriteHeader(http.StatusNoContent)
	case p == "/api/v1/repos/search":
		var all []map[string]any
		for _, n := range keys(f.repos) {
			all = append(all, map[string]any{"full_name": n, "default_branch": "main", "empty": len(f.repos[n]) == 0})
		}
		writeJSON(w, map[string]any{"ok": true, "data": pageOf(all, page, pageSize)})
	case treePath.MatchString(p):
		m := treePath.FindStringSubmatch(p)
		full := m[1] + "/" + m[2]
		if f.broken[full] {
			http.Error(w, "boom", http.StatusInternalServerError)
			return
		}
		var tree []map[string]any
		for _, path := range keys(f.repos[full]) {
			tree = append(tree, map[string]any{"path": path, "type": "blob"})
		}
		writeJSON(w, map[string]any{"tree": tree, "truncated": false, "total_count": len(tree)})
	case rawPath.MatchString(p):
		m := rawPath.FindStringSubmatch(p)
		file, _ := url.PathUnescape(m[3])
		content, has := f.repos[m[1]+"/"+m[2]][file]
		if !has {
			http.NotFound(w, r)
			return
		}
		w.Write([]byte(content))
	default:
		http.NotFound(w, r)
	}
}

func keys[T any](m map[string]T) []string {
	var out []string
	for k := range m {
		out = append(out, k)
	}
	sort.Strings(out)
	return out
}

func pageOf[T any](all []T, page, size int) []T {
	lo := (page - 1) * size
	if lo >= len(all) {
		return []T{}
	}
	return all[lo:min(lo+size, len(all))]
}

func writeJSON(w http.ResponseWriter, v any) {
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(v)
}

// aRegistry: the SDK with nine versions over two lines, a UI package with three, and repositories that
// pin an old SDK in a lockfile, range onto the old line, and tag a pre-release.
func aRegistry(t *testing.T) *fakeForge {
	return &fakeForge{
		t:        t,
		password: "s3cret-never-shown",
		versions: map[string][]string{
			"@acme/sdk": {"0.1.0", "0.1.1", "0.1.2", "0.1.3", "0.2.0", "0.2.1", "0.2.2", "0.3.0-beta.1", "0.3.0"},
			"@acme/ui":  {"1.0.0", "1.1.0", "2.0.0"},
		},
		tags: map[string]map[string]string{
			"@acme/sdk": {"latest": "0.3.0", "next": "0.3.0-beta.1"},
			"@acme/ui":  {"latest": "2.0.0"},
		},
		repos: map[string]map[string]string{
			"acme/app": {
				"package.json":      `{"dependencies":{"@acme/sdk":"^0.1.0","left-pad":"1.0.0"}}`,
				"package-lock.json": `{"lockfileVersion":3,"packages":{"node_modules/@acme/sdk":{"version":"0.1.0"}}}`,
			},
			"acme/site":  {"web/package.json": `{"devDependencies":{"@acme/ui":"~1.0.0"}}`, "README.md": "x"},
			"acme/empty": {},
		},
	}
}

func decided(s *Survey) map[string]Item {
	out := map[string]Item{}
	for _, p := range s.Packages {
		for _, v := range p.Versions {
			out[p.Name+"@"+v.Version] = v
		}
	}
	return out
}

func TestWhatKeepsAVersionIsWhatNamesIt(t *testing.T) {
	f := aRegistry(t)
	s, err := survey(context.Background(), f.serve(), "", 3, func(Item) bool { return true })
	if err != nil {
		t.Fatal(err)
	}
	if s.Repositories != 3 || len(s.Unread) != 0 {
		t.Fatalf("read %d, unread %v", s.Repositories, s.Unread)
	}
	d := decided(s)
	wantKept := map[string]string{
		"@acme/sdk@0.1.0":        "a lockfile names it: acme/app:package-lock.json", // old, but pinned
		"@acme/sdk@0.1.3":        "the highest version satisfying ^0.1.0 in acme/app:package.json",
		"@acme/sdk@0.3.0-beta.1": "dist-tag next",
		"@acme/sdk@0.3.0":        "dist-tag latest",
		"@acme/sdk@0.2.2":        "among the newest 3 (pre-releases count)",
		"@acme/ui@1.0.0":         "the highest version satisfying ~1.0.0 in acme/site:web/package.json",
		"@acme/ui@1.1.0":         "among the newest 3 (pre-releases count)",
	}
	for v, why := range wantKept {
		item := d[v]
		if !item.Kept || !contains(item.Why, why) {
			t.Errorf("%s: kept %v, why %v; want %q", v, item.Kept, item.Why, why)
		}
	}
	for _, v := range []string{"@acme/sdk@0.1.1", "@acme/sdk@0.1.2", "@acme/sdk@0.2.0", "@acme/sdk@0.2.1"} {
		if d[v].Kept {
			t.Errorf("%s kept for %v", v, d[v].Why)
		}
	}
	if d["@acme/sdk@0.1.1"].Bytes != 1<<20+1024 {
		t.Errorf("size %d", d["@acme/sdk@0.1.1"].Bytes)
	}
	// Newest first.
	if s.Packages[0].Versions[0].Version != "0.3.0" || s.Packages[0].Versions[1].Version != "0.3.0-beta.1" {
		t.Errorf("order %v", s.Packages[0].Versions[:2])
	}
}

func contains(list []string, s string) bool {
	for _, x := range list {
		if x == s {
			return true
		}
	}
	return false
}

func TestADryRunDeletesNothingAndSaysWhatWouldGo(t *testing.T) {
	f := aRegistry(t)
	p, err := retention(context.Background(), f.serve(), "", 3, true, "")
	if err != nil {
		t.Fatal(err)
	}
	if len(f.deleted) != 0 {
		t.Fatalf("a dry run deleted %v", f.deleted)
	}
	var would []string
	for _, c := range p.Candidates {
		would = append(would, c.Package+"@"+c.Version)
	}
	sort.Strings(would)
	if strings.Join(would, " ") != "@acme/sdk@0.1.1 @acme/sdk@0.1.2 @acme/sdk@0.2.0 @acme/sdk@0.2.1" {
		t.Fatalf("would delete %v", would)
	}
	if p.Bytes != 4*(1<<20+1024) {
		t.Errorf("bytes %d", p.Bytes)
	}
	raw, _ := json.Marshal(p)
	if strings.Contains(string(raw), f.password) {
		t.Fatal("the answer carries the forge's password")
	}
}

func TestARealRunWithoutWhyIsRefusedBeforeAnythingIsRead(t *testing.T) {
	f := aRegistry(t)
	if _, err := retention(context.Background(), f.serve(), "", 3, false, "  "); err == nil || !strings.Contains(err.Error(), "needs why") {
		t.Fatalf("got %v", err)
	}
	if len(f.deleted) != 0 {
		t.Fatal("deleted without a why")
	}
}

func TestARealRunDeletesOnlyWhatNothingKeeps(t *testing.T) {
	f := aRegistry(t)
	p, err := retention(context.Background(), f.serve(), "", 3, false, "the registry keeps what is named")
	if err != nil {
		t.Fatal(err)
	}
	sort.Strings(f.deleted)
	if strings.Join(f.deleted, " ") != "@acme/sdk@0.1.1 @acme/sdk@0.1.2 @acme/sdk@0.2.0 @acme/sdk@0.2.1" {
		t.Fatalf("deleted %v", f.deleted)
	}
	if len(p.Deleted) != 4 || len(p.Refused) != 0 {
		t.Fatalf("answered %v / %v", p.Deleted, p.Refused)
	}
}

func TestAnUnreadRepositoryStopsARealRunBeforeAnythingIsDeleted(t *testing.T) {
	f := aRegistry(t)
	f.broken = map[string]bool{"acme/site": true}
	p, err := retention(context.Background(), f.serve(), "", 3, false, "tidy")
	if err == nil || !strings.Contains(err.Error(), "nothing was deleted") {
		t.Fatalf("got %v", err)
	}
	if len(f.deleted) != 0 {
		t.Fatalf("deleted %v while a repository was unread", f.deleted)
	}
	if p == nil || len(p.Unread) != 1 || !strings.HasPrefix(p.Unread[0], "acme/site") {
		t.Fatalf("unread %v", p)
	}
	// And the dry run says so, without failing.
	dry, err := retention(context.Background(), f.serve(), "", 3, true, "")
	if err != nil || len(dry.Unread) != 1 {
		t.Fatalf("dry run: %v %v", err, dry)
	}
}

func TestARangeThatCannotBeReadKeepsEveryVersionOfItsPackage(t *testing.T) {
	f := aRegistry(t)
	f.repos["acme/odd"] = map[string]string{"package.json": `{"dependencies":{"@acme/sdk":"^not.a.range"}}`}
	p, err := retention(context.Background(), f.serve(), "@acme/sdk", 1, true, "")
	if err != nil {
		t.Fatal(err)
	}
	if len(p.Candidates) != 0 || !strings.Contains(p.Packages[0].KeepsAll, "^not.a.range") {
		t.Fatalf("candidates %v, keeps all %q", p.Candidates, p.Packages[0].KeepsAll)
	}
}

func TestADistTagNamedAsARangeKeepsItsVersion(t *testing.T) {
	f := aRegistry(t)
	f.repos["acme/tagged"] = map[string]string{"package.json": `{"dependencies":{"@acme/sdk":"next"}}`}
	s, err := survey(context.Background(), f.serve(), "@acme/sdk", 1, nil)
	if err != nil {
		t.Fatal(err)
	}
	if s.Packages[0].KeepsAll != "" || !decided(s)["@acme/sdk@0.3.0-beta.1"].Kept {
		t.Fatalf("%+v", s.Packages[0])
	}
}

func TestAWrongPasswordIsAFailureThatDoesNotSayThePassword(t *testing.T) {
	f := aRegistry(t)
	forge := f.serve()
	f.password = "rotated"
	_, err := survey(context.Background(), forge, "", 3, nil)
	if err == nil || !strings.Contains(err.Error(), "401") || strings.Contains(err.Error(), "s3cret") {
		t.Fatalf("got %v", err)
	}
}

func TestToolsAreTheOnesTheReadmeNamesAndSayWhatTheyDo(t *testing.T) {
	tools := Tools(func() (*Forge, error) { return nil, fmt.Errorf("unset") })
	var served []string
	for _, tl := range tools {
		served = append(served, tl.Name)
		suffix := "(r)"
		if tl.Name == "npm_retention" {
			suffix = "(a)"
		}
		if !strings.HasSuffix(tl.Description, suffix) {
			t.Errorf("%s does not end with %s", tl.Name, suffix)
		}
	}
	if strings.Join(served, ",") != strings.Join(ToolNames, ",") {
		t.Fatalf("served %v, named %v", served, ToolNames)
	}
	readme, err := os.ReadFile("../../README.md")
	if err != nil {
		t.Fatal(err)
	}
	for _, n := range ToolNames {
		if !strings.Contains(string(readme), "`"+n+"`") {
			t.Errorf("the README does not name %s", n)
		}
	}
	raw, err := os.ReadFile("../../module.json")
	if err != nil {
		t.Fatal(err)
	}
	var m struct {
		Tools []string `json:"tools"`
		Build struct {
			Artifacts []struct {
				From  string            `json:"from"`
				Loads []string          `json:"loads"`
				Env   map[string]string `json:"env"`
			} `json:"artifacts"`
		} `json:"build"`
	}
	if err := json.Unmarshal(raw, &m); err != nil {
		t.Fatal(err)
	}
	if len(m.Tools) != 0 {
		t.Error("the manifest lists tools: its claims would offer them as both seats' verbs")
	}
	found := false
	for _, a := range m.Build.Artifacts {
		if a.From == "cmd/npm-registry" {
			found = true
			for _, k := range []string{"MESH_GITEA_URL", "MESH_GITEA_ADMIN_USER", "MESH_GITEA_ADMIN_PASSWORD_FILE", "MESH_NPM_OWNER"} {
				if a.Env[k] == "" {
					t.Errorf("the bundle is not given %s", k)
				}
			}
		}
	}
	if !found {
		t.Error("the manifest builds no cmd/npm-registry bundle")
	}
	// Refused cleanly when the environment is missing, not a crash.
	if _, err := tools[0].Run(map[string]any{}); err == nil {
		t.Error("ran without a forge")
	}
}

func TestEveryVersionIsMeasuredAndASizeNotReadIsSaid(t *testing.T) {
	f := aRegistry(t)
	f.files = map[string][]int64{"@acme/sdk@0.1.1": {1000, 234}, "@acme/sdk@0.3.0": {5000}}
	f.noSize = map[string]bool{"@acme/sdk@0.2.0": true}
	p, err := retention(context.Background(), f.serve(), "@acme/sdk", 3, true, "")
	if err != nil {
		t.Fatal(err)
	}
	d := decided(p.Survey)
	// A kept version is measured too: no 0 that nobody asked for.
	if got := d["@acme/sdk@0.3.0"]; !got.Kept || got.Bytes != 5000 || got.SizeError != "" {
		t.Errorf("kept 0.3.0: %+v", got)
	}
	if got := d["@acme/sdk@0.1.1"]; got.Bytes != 1234 {
		t.Errorf("0.1.1: %+v", got)
	}
	broken := d["@acme/sdk@0.2.0"]
	if broken.Bytes != 0 || !strings.Contains(broken.SizeError, "500") {
		t.Errorf("0.2.0: %+v", broken)
	}
	var candidate *Candidate
	for i := range p.Candidates {
		if p.Candidates[i].Version == "0.2.0" {
			candidate = &p.Candidates[i]
		}
	}
	if candidate == nil || candidate.SizeError == "" {
		t.Errorf("the candidate does not carry its size error: %+v", p.Candidates)
	}
	// Would delete 0.1.1 (1234), 0.1.2 and 0.2.1 (1 MiB + 1 KiB each) and 0.2.0 (unknown).
	if want := int64(1234 + 2*(1<<20+1024)); p.Bytes != want {
		t.Errorf("bytes %d, want %d", p.Bytes, want)
	}
	if p.RegistryBytes <= p.Bytes {
		t.Errorf("registry bytes %d not above %d", p.RegistryBytes, p.Bytes)
	}
	said := strings.Join(p.Said, "\n")
	if !strings.Contains(said, "the size of 1 versions could not be read") || !strings.Contains(said, "@acme/sdk@0.2.0") {
		t.Errorf("said %q", said)
	}
}

func TestALockfileOfEveryShapeKeepsWhatItPins(t *testing.T) {
	f := aRegistry(t)
	f.repos["acme/v2"] = map[string]string{"package-lock.json": `{"lockfileVersion":2,"packages":{
		"":{"name":"v2","dependencies":{"@acme/sdk":"^0.2.0"}},
		"node_modules/@acme/sdk":{"version":"0.2.0","dependencies":{"left-pad":"^1.0.0"}}},
		"dependencies":{"@acme/sdk":{"version":"0.2.0","requires":{"left-pad":"^1.0.0"}}}}`}
	s, err := survey(context.Background(), f.serve(), "@acme/sdk", 1, nil)
	if err != nil {
		t.Fatal(err)
	}
	if len(s.NotRead) != 0 {
		t.Fatalf("not read %v", s.NotRead)
	}
	if got := decided(s)["@acme/sdk@0.2.0"]; !contains(got.Why, "a lockfile names it: acme/v2:package-lock.json") {
		t.Fatalf("0.2.0: %+v", got)
	}
}

func TestAnUnreadableLockfileStopsARealRunBeforeAnythingIsDeleted(t *testing.T) {
	f := aRegistry(t)
	f.repos["acme/odd"] = map[string]string{"package-lock.json": `{"lockfileVersion":3,"packages":{`}
	p, err := retention(context.Background(), f.serve(), "", 3, false, "tidy")
	if err == nil || !strings.Contains(err.Error(), "nothing was deleted") || !strings.Contains(err.Error(), "acme/odd:package-lock.json") {
		t.Fatalf("got %v", err)
	}
	if len(f.deleted) != 0 {
		t.Fatalf("deleted %v while a lockfile was not read", f.deleted)
	}
	if p == nil || len(p.NotRead) != 1 || len(p.Deleted) != 0 {
		t.Fatalf("plan %+v", p)
	}
	// And the dry run says so, without failing, and still says what would go.
	dry, err := retention(context.Background(), f.serve(), "", 3, true, "")
	if err != nil || len(dry.NotRead) != 1 || len(dry.Candidates) == 0 {
		t.Fatalf("dry run: %v %+v", err, dry)
	}
	if !strings.Contains(strings.Join(dry.Said, "\n"), "1 files were not read whole") {
		t.Errorf("said %v", dry.Said)
	}
}

// An answer larger than the cap is refused, never parsed as if the cut body were whole; one exactly at
// the cap is read.
func TestAnAnswerTheCapCutIsRefused(t *testing.T) {
	size := maxBody + 1
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write(make([]byte, size))
	}))
	t.Cleanup(srv.Close)
	file := filepath.Join(t.TempDir(), "admin.secret")
	if err := os.WriteFile(file, []byte("x\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	f := &Forge{URL: srv.URL, User: "admin", PasswordFile: file, Owner: "acme"}
	if _, err := f.do(context.Background(), http.MethodGet, "/big"); err == nil || !strings.Contains(err.Error(), "not read whole") {
		t.Fatalf("a cut answer: %v", err)
	}
	size = maxBody
	if body, err := f.do(context.Background(), http.MethodGet, "/big"); err != nil || len(body) != maxBody {
		t.Fatalf("an answer at the cap: %d bytes, %v", len(body), err)
	}
}