package engine

import (
	"context"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"sync/atomic"
	"testing"
	"time"

	"jarl/internal/blocking"
	"jarl/internal/model"
)

func blockRule(name, action string, exact bool, views ...string) Request {
	in := BlockRuleInput{Name: &name, Action: &action, Exact: &exact}
	if len(views) > 0 {
		in.Views = &views
	}
	return NewRequest(OpBlockRuleCreate, 0, in)
}

func blocklist(name, url string, views ...string) Request {
	in := BlocklistInput{Name: &name, URL: &url}
	if len(views) > 0 {
		in.Views = &views
	}
	return NewRequest(OpBlocklistCreate, 0, in)
}

// listServer serves a blocklist with an ETag, and counts the downloads
// that sent content.
type listServer struct {
	body  atomic.Value
	full  atomic.Int32
	calls atomic.Int32
}

func newListServer(t *testing.T, body string) (*listServer, *httptest.Server) {
	ls := &listServer{}
	ls.body.Store(body)
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		ls.calls.Add(1)
		b := ls.body.Load().(string)
		etag := `"` + string(rune('a'+len(b)%26)) + "x" + string(rune('a'+len(b)/26%26)) + `"`
		if r.Header.Get("If-None-Match") == etag {
			w.WriteHeader(http.StatusNotModified)
			return
		}
		w.Header().Set("ETag", etag)
		ls.full.Add(1)
		w.Write([]byte(b))
	}))
	t.Cleanup(srv.Close)
	return ls, srv
}

func TestBlockingRender(t *testing.T) {
	env := newEnv(t)
	setupZone(env)
	env.submit(env.admin,
		NewRequest(OpViewCreate, 0, ViewInput{Name: model.Ptr("internal"), MatchClients: &[]string{"10.0.0.0/8"}, AdoptZones: true}),
		NewRequest(OpViewCreate, 0, ViewInput{Name: model.Ptr("external")}),
	)
	st := env.state()
	ext := st.ViewByName("external")
	env.submit(env.admin, NewRequest(OpOptionCreate, 0, OptionInput{Scope: model.Ptr(model.ScopeView), ScopeID: &ext.ID, Name: model.Ptr("recursion"), Value: model.Ptr("no")}))

	_, srv := newListServer(t, "||ads.example^\n")
	res := env.submit(env.admin,
		blocklist("ads", srv.URL+"/list.txt"),
		blockRule("tracker.example", "block", false),
		blockRule("cdn.tracker.example", "allow", true),
	)
	if res.Ops[1].Summary != "block tracker.example (and below)" || res.Ops[2].Summary != "allow cdn.tracker.example" {
		t.Errorf("summaries: %q, %q", res.Ops[1].Summary, res.Ops[2].Summary)
	}
	conf, _ := os.ReadFile(filepath.Join(env.dir, "etc/named.conf"))
	c := string(conf)
	// Automatic views: only internal offers recursion.
	internal := c[strings.Index(c, `view "internal"`):strings.Index(c, `view "external"`)]
	for _, want := range []string{
		"response-policy {\n\t\tzone \"rules.jarl.invalid\" min-update-interval 0 log no;\n\t\tzone \"ads.blocklist.jarl.invalid\" min-update-interval 0 log no;\n\t} qname-wait-recurse no break-dnssec yes;",
		`zone "rules.jarl.invalid" {`,
		"allow-query { none; };",
	} {
		if !strings.Contains(internal, want) {
			t.Errorf("view internal lacks %q:\n%s", want, internal)
		}
	}
	if strings.Contains(c[strings.Index(c, `view "external"`):], "response-policy") {
		t.Error("view external, without recursion, got blocking")
	}
	rules, err := os.ReadFile(filepath.Join(env.dir, "zones/internal/rules.jarl.invalid.rpz"))
	if err != nil || !strings.Contains(string(rules), "cdn.tracker.example\tCNAME\trpz-passthru.\n*.cdn.tracker.example\tCNAME\t.\n") {
		t.Errorf("rules zone: %v\n%s", err, rules)
	}
	// The list's file exists as an empty policy zone until downloaded.
	b := env.state().BlocklistByName("ads")
	listFile := filepath.Join(env.dir, "cache/blocklists/list-"+strconv.FormatInt(b.ID, 10)+".rpz")
	if f, err := os.ReadFile(listFile); err != nil || !strings.Contains(string(f), "not downloaded yet") {
		t.Errorf("placeholder: %v %s", err, f)
	}

	// A view a list or rule names can't be deleted.
	res = env.submit(env.admin, NewRequest(OpBlocklistUpdate, b.ID, BlocklistInput{Views: &[]string{"external"}}))
	if len(res.Problems) != 1 || res.Problems[0].Code != "blocking_no_recursion" {
		t.Errorf("a list in a view without recursion: %+v", res.Problems)
	}
	if e := env.submitErr(env.admin, NewRequest(OpViewDelete, ext.ID, DeleteInput{Cascade: true})); e.Kind != KindConflict || !strings.Contains(e.Message, "blocklist ads") {
		t.Errorf("deleting a used view: %+v", e)
	}
	st = env.state()
	// A second rule for the same name and view is refused.
	if e := env.submitErr(env.admin, blockRule("tracker.example", "allow", true)); e.Kind != KindValidation || !strings.Contains(e.Message, "two rules for tracker.example") {
		t.Errorf("duplicate rule: %+v", e)
	}
	// So is a response-policy option where Jarl writes one.
	in := st.ViewByName("internal")
	if e := env.submitErr(env.admin, NewRequest(OpOptionCreate, 0, OptionInput{Scope: model.Ptr(model.ScopeView), ScopeID: &in.ID, Name: model.Ptr("response-policy"), Value: model.Ptr(`{ zone "x"; }`)})); e.Kind != KindValidation {
		t.Errorf("response-policy option: %+v", e)
	}
	// Bad input.
	for _, req := range []Request{blocklist("Bad Name", srv.URL), blocklist("ok", "ftp://x/list"), blockRule("com", "block", false), blockRule("a.example", "deny", false), blockRule("a.example", "block", false, "nope")} {
		if e := env.submitErr(env.admin, req); e.Kind != KindBadRequest {
			t.Errorf("%s: %+v", req.Data, e)
		}
	}
}

func TestBlocklistRefresh(t *testing.T) {
	env := newEnv(t)
	setupZone(env)
	ls, srv := newListServer(t, "# test\n||ads.example^\n0.0.0.0 tracker.example\nnot a domain line\n")
	env.submit(env.admin, blocklist("ads", srv.URL), blockRule("good.ads.example", "allow", false))
	b := env.state().BlocklistByName("ads")
	ctx := context.Background()

	env.e.RefreshDue(ctx)
	s, _ := env.st.BlocklistStatuses(ctx)
	st := s[b.ID]
	if st == nil || st.Error != "" || st.Entries != 2 || st.Records != 3 || st.Skipped != 1 || st.UpdatedAt == nil {
		t.Fatalf("status after the first download: %+v", st)
	}
	file := env.e.cfg.Paths.BlocklistFile(b.ID)
	if f, _ := os.ReadFile(file); !strings.Contains(string(f), "*.ads.example\tCNAME\t.\n") || !strings.Contains(string(f), "tracker.example\tCNAME\t.\n") {
		t.Errorf("list zone:\n%s", f)
	}
	// Not due again: nothing is fetched.
	env.e.RefreshDue(ctx)
	if ls.calls.Load() != 1 {
		t.Errorf("downloads after a second RefreshDue: %d", ls.calls.Load())
	}
	// A cleared cache leaves an empty placeholder: downloaded again at once.
	os.Remove(file)
	env.e.RefreshDue(ctx)
	if ls.calls.Load() != 2 {
		t.Errorf("downloads after the file was lost: %d", ls.calls.Load())
	}
	if f, _ := os.ReadFile(file); !strings.Contains(string(f), "*.ads.example\tCNAME\t.\n") {
		t.Errorf("list zone after the file was lost:\n%s", f)
	}
	// Unchanged on the server: 304, no rewrite.
	firstHash := st.SHA256
	fullBefore := ls.full.Load()
	env.e.RefreshBlocklist(ctx, b.ID, false)
	if ls.full.Load() != fullBefore {
		t.Errorf("a conditional download fetched the list again")
	}
	// Changed: rewritten.
	ls.body.Store("||ads.example^\n||more.example^\n")
	st, err := env.e.RefreshBlocklist(ctx, b.ID, false)
	if err != nil || st.Entries != 2 || st.Records != 4 || st.SHA256 == firstHash {
		t.Errorf("after a change: %+v, %v", st, err)
	}
	// A broken download keeps the previous version and reports why.
	before, _ := os.ReadFile(file)
	ls.body.Store("<html><body>Not found</body></html>\n")
	st, err = env.e.RefreshBlocklist(ctx, b.ID, true)
	if err == nil || !strings.Contains(st.Error, "no domains found") {
		t.Errorf("garbage: %+v, %v", st, err)
	}
	if after, _ := os.ReadFile(file); string(after) != string(before) {
		t.Error("a failed update changed the list's file")
	}
	// A failed attempt is retried after RetryAfter, not at every check.
	calls := ls.calls.Load()
	env.e.RefreshDue(ctx)
	if ls.calls.Load() != calls {
		t.Error("a failed list was tried again before RetryAfter")
	}
	// Too big.
	env.e.Limits.MaxBytes = 10
	ls.body.Store("||ads.example^\n||more.example^\n||third.example^\n")
	if st, _ = env.e.RefreshBlocklist(ctx, b.ID, true); !strings.Contains(st.Error, "larger than") {
		t.Errorf("size limit: %+v", st)
	}
	env.e.Limits = DefaultBlocklistLimits()
	env.e.RefreshBlocklist(ctx, b.ID, true)

	// What blocks what.
	check := func(name string) blocking.Match {
		m, err := env.e.CheckBlocking(env.state(), name)
		if err != nil || len(m) != 1 {
			t.Fatalf("check %s: %+v %v", name, m, err)
		}
		return m[0]
	}
	if m := check("x.ads.example"); m.Result != "blocked" || m.List != "ads" || m.Entry != "*.ads.example" {
		t.Errorf("x.ads.example: %+v", m)
	}
	if m := check("a.good.ads.example"); m.Result != "allowed" || m.RuleID == 0 || m.Entry != "*.good.ads.example" {
		t.Errorf("a.good.ads.example: %+v", m)
	}
	if m := check("fine.example"); m.Result != "none" {
		t.Errorf("fine.example: %+v", m)
	}

	// Deleting the list removes its file and status.
	env.submit(env.admin, NewRequest(OpBlocklistDelete, b.ID, nil))
	env.e.RefreshDue(ctx)
	if _, err := os.Stat(file); !os.IsNotExist(err) {
		t.Errorf("the deleted list's file is still there: %v", err)
	}
	if s, _ := env.st.BlocklistStatuses(ctx); s[b.ID] != nil {
		t.Error("the deleted list's status is still there")
	}
}

func TestBlockingPause(t *testing.T) {
	env := newEnv(t)
	setupZone(env)
	env.submit(env.admin, blocklist("ads", "https://example.org/list"))
	rulesFile := filepath.Join(env.dir, "zones/_default/rules.jarl.invalid.rpz")
	if _, err := os.Stat(rulesFile); !os.IsNotExist(err) {
		t.Fatal("a rules zone without rules or a pause")
	}
	until := env.e.Now().Add(10 * time.Minute)
	res := env.submit(env.admin, NewRequest(OpBlockingPause, 0, BlockingPauseInput{Until: &until}))
	if !strings.HasPrefix(res.Ops[0].Summary, "pause blocking until ") {
		t.Errorf("summary = %q", res.Ops[0].Summary)
	}
	f, err := os.ReadFile(rulesFile)
	if err != nil || !strings.HasSuffix(string(f), "NS\tlocalhost.\n*\tCNAME\trpz-passthru.\n") {
		t.Fatalf("paused rules zone: %v\n%s", err, f)
	}
	conf, _ := os.ReadFile(filepath.Join(env.dir, "etc/named.conf"))
	if !strings.Contains(string(conf), "zone \"rules.jarl.invalid\" min-update-interval 0 log no;\n\t\tzone \"ads.") {
		t.Errorf("the paused rules zone must come first:\n%s", conf)
	}
	// Not yet time: nothing happens.
	if got := env.e.ResumeBlocking(context.Background()); !got.Equal(until) {
		t.Errorf("ResumeBlocking before the end = %v", got)
	}
	// Time is up: resumed, and the rules zone is gone again.
	env.submit(env.admin, blockRule("ads.example", "block", false))
	env.e.Now = func() time.Time { return until.Add(time.Second) }
	if got := env.e.ResumeBlocking(context.Background()); !got.IsZero() || env.state().Settings.BlockingPausedUntil != nil {
		t.Fatalf("after the pause: %v, %v", got, env.state().Settings.BlockingPausedUntil)
	}
	if f, _ := os.ReadFile(rulesFile); !strings.Contains(string(f), "*.ads.example\tCNAME\t.\n") || strings.Contains(string(f), "passthru") {
		t.Errorf("rules zone after the pause:\n%s", f)
	}
	// Reverting a pause resumes blocking.
	until = env.e.Now().Add(time.Hour)
	res = env.submit(env.admin, NewRequest(OpBlockingPause, 0, BlockingPauseInput{Until: &until}))
	rev, err := env.e.Revert(context.Background(), res.ChangesetID, env.admin)
	if err != nil {
		t.Fatal(err)
	}
	if _, err := env.e.Apply(context.Background(), rev.ID, env.admin, ApplyOptions{}); err != nil || env.state().Settings.BlockingPausedUntil != nil {
		t.Errorf("revert of a pause: %v, %v", err, env.state().Settings.BlockingPausedUntil)
	}
	// At most a day.
	long := env.e.Now().Add(48 * time.Hour)
	if e := env.submitErr(env.admin, NewRequest(OpBlockingPause, 0, BlockingPauseInput{Until: &long})); e.Kind != KindBadRequest {
		t.Errorf("a two-day pause: %+v", e)
	}
}