package handlers_test

import (
	"context"
	"errors"
	"fmt"
	"html/template"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"strconv"
	"sync"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"go.uber.org/fx"
	"go.uber.org/fx/fxtest"
	"sneak.berlin/go/webhooker/internal/archive"
	"sneak.berlin/go/webhooker/internal/config"
	"sneak.berlin/go/webhooker/internal/database"
	"sneak.berlin/go/webhooker/internal/delivery"
	"sneak.berlin/go/webhooker/internal/globals"
	"sneak.berlin/go/webhooker/internal/handlers"
	"sneak.berlin/go/webhooker/internal/healthcheck"
	"sneak.berlin/go/webhooker/internal/logger"
	"sneak.berlin/go/webhooker/internal/metrics"
	"sneak.berlin/go/webhooker/internal/middleware"
	"sneak.berlin/go/webhooker/internal/session"
)

// recordingNotifier is a delivery.Notifier that records the tasks it
// was handed, so a test can prove a handler queued the delivery it
// claims to have queued — and, on the refusal paths, that it queued
// nothing.
type recordingNotifier struct {
	mu    sync.Mutex
	tasks []delivery.Task
}

func (n *recordingNotifier) Notify(tasks []delivery.Task) {
	n.mu.Lock()
	defer n.mu.Unlock()

	n.tasks = append(n.tasks, tasks...)
}

// Tasks returns a copy of the recorded tasks.
func (n *recordingNotifier) Tasks() []delivery.Task {
	n.mu.Lock()
	defer n.mu.Unlock()

	out := make([]delivery.Task, len(n.tasks))
	copy(out, n.tasks)

	return out
}

// recordingArchives is an archive.Archives that records what it
// was asked to do, so a test can prove that a deletion or rename
// path reached the archive writers. After FailRenames, every
// rename of that target fails with the given error. After
// BlockNextRename, the next rename is recorded and then waits.
// RenameLock returns a plain mutex, as in archive.Writers.
type recordingArchives struct {
	renameMu       sync.Mutex
	mu             sync.Mutex
	evicted        []string
	evictedTargets []string
	renames        []archiveRename
	renameErrs     map[string]error
	entered        chan struct{}
	release        chan struct{}
}

// errInjectedRename is the failure a test hands FailRenames.
var errInjectedRename = errors.New("injected rename failure")

// errNameTaken is what the archive writers return when a file
// already has an archive's new name, here archive-taken.db.
var errNameTaken = fmt.Errorf(
	"%w: archive-taken.db", archive.ErrNameTaken,
)

// archiveRename is one recorded Rename call.
type archiveRename struct {
	TargetID    string
	WebhookName string
	TargetName  string
}

func (r *recordingArchives) RenameLock() *sync.Mutex {
	return &r.renameMu
}

func (r *recordingArchives) EvictWebhook(webhookID string) {
	r.mu.Lock()
	defer r.mu.Unlock()

	r.evicted = append(r.evicted, webhookID)
}

func (r *recordingArchives) EvictTarget(targetID string) {
	r.mu.Lock()
	defer r.mu.Unlock()

	r.evictedTargets = append(r.evictedTargets, targetID)
}

func (r *recordingArchives) Rename(
	targetID, webhookName, targetName string,
) error {
	r.mu.Lock()

	r.renames = append(r.renames, archiveRename{
		TargetID:    targetID,
		WebhookName: webhookName,
		TargetName:  targetName,
	})
	err := r.renameErrs[targetID]
	entered, release := r.entered, r.release
	r.entered, r.release = nil, nil

	r.mu.Unlock()

	if entered != nil {
		close(entered)
		<-release
	}

	return err
}

// BlockNextRename makes the next rename, once recorded, wait until
// the returned release is called. The returned channel is closed
// when that rename starts waiting.
func (r *recordingArchives) BlockNextRename() (<-chan struct{}, func()) {
	entered := make(chan struct{})
	release := make(chan struct{})

	r.mu.Lock()
	r.entered, r.release = entered, release
	r.mu.Unlock()

	return entered, func() { close(release) }
}

// FailRenames makes every later rename of targetID fail with err.
func (r *recordingArchives) FailRenames(targetID string, err error) {
	r.mu.Lock()
	defer r.mu.Unlock()

	if r.renameErrs == nil {
		r.renameErrs = map[string]error{}
	}

	r.renameErrs[targetID] = err
}

// Evicted returns a copy of the recorded webhook ids.
func (r *recordingArchives) Evicted() []string {
	r.mu.Lock()
	defer r.mu.Unlock()

	out := make([]string, len(r.evicted))
	copy(out, r.evicted)

	return out
}

// EvictedTargets returns a copy of the recorded target ids.
func (r *recordingArchives) EvictedTargets() []string {
	r.mu.Lock()
	defer r.mu.Unlock()

	out := make([]string, len(r.evictedTargets))
	copy(out, r.evictedTargets)

	return out
}

// Renames returns a copy of the recorded renames.
func (r *recordingArchives) Renames() []archiveRename {
	r.mu.Lock()
	defer r.mu.Unlock()

	out := make([]archiveRename, len(r.renames))
	copy(out, r.renames)

	return out
}

// testCircuitBreakers is a delivery.CircuitBreakers that reports, for
// each target, the circuit state and cooldown a test gave it with Set,
// and a closed breaker for any other target.
type testCircuitBreakers struct {
	mu        sync.Mutex
	states    map[string]delivery.CircuitState
	cooldowns map[string]time.Duration
}

// Set makes the target's breaker read as state, with cooldown left.
func (b *testCircuitBreakers) Set(
	targetID string, state delivery.CircuitState, cooldown time.Duration,
) {
	b.mu.Lock()
	defer b.mu.Unlock()

	if b.states == nil {
		b.states = map[string]delivery.CircuitState{}
		b.cooldowns = map[string]time.Duration{}
	}

	b.states[targetID] = state
	b.cooldowns[targetID] = cooldown
}

func (b *testCircuitBreakers) StateAndCooldown(
	targetID string,
) (delivery.CircuitState, time.Duration) {
	b.mu.Lock()
	defer b.mu.Unlock()

	return b.states[targetID], b.cooldowns[targetID]
}

// newTestApp returns an app whose RequireStart fails the test when
// starting takes longer than fx's default start timeout of 15s. That
// limit catches a start that hangs, not a busy host: measured with make
// test on 2026-10-02 at host load 58-69 on 48 cores, the slowest of this
// package's starts took 0.49s.
func newTestApp(
	t *testing.T,
	targets ...any,
) *fxtest.App {
	t.Helper()

	return newTestAppWithConfig(
		t, &config.Config{DataDir: t.TempDir()}, targets...,
	)
}

// newTestAppWithConfig is newTestApp over a caller-supplied Config.
func newTestAppWithConfig(
	t *testing.T,
	cfg *config.Config,
	targets ...any,
) *fxtest.App {
	t.Helper()

	return fxtest.New(
		t,
		// fx's own log is discarded, not sent to t.Logf: a hook still
		// running after a start or stop timeout would write there after
		// the test has returned.
		fx.NopLogger,
		fx.Provide(
			globals.New,
			logger.New,
			func(l *logger.Logger) *slog.Logger { return l.Get() },
			func() *config.Config { return cfg },
			database.New,
			database.NewWebhookDBManager,
			healthcheck.New,
			session.New,
			func() *recordingNotifier {
				return &recordingNotifier{}
			},
			func(n *recordingNotifier) delivery.Notifier {
				return n
			},
			func() *recordingArchives {
				return &recordingArchives{}
			},
			func(r *recordingArchives) archive.Archives {
				return r
			},
			func() *testCircuitBreakers {
				return &testCircuitBreakers{}
			},
			func(b *testCircuitBreakers) delivery.CircuitBreakers {
				return b
			},
			metrics.NewRegistry,
			metrics.New,
			middleware.New,
			delivery.NewGuard,
			handlers.New,
		),
		fx.Populate(targets...),
	)
}

func TestHandleIndex_Unauthenticated(t *testing.T) {
	t.Parallel()

	var h *handlers.Handlers

	app := newTestApp(t, &h)
	app.RequireStart()

	t.Cleanup(app.RequireStop)

	req := httptest.NewRequestWithContext(
		context.Background(), http.MethodGet, "/", nil)
	w := httptest.NewRecorder()

	handler := h.HandleIndex()
	handler.ServeHTTP(w, req)

	assert.Equal(t, http.StatusSeeOther, w.Code)
	assert.Equal(
		t, "/pages/login", w.Header().Get("Location"),
	)
}

func TestHandleIndex_Authenticated(t *testing.T) {
	t.Parallel()

	var h *handlers.Handlers

	var sess *session.Session

	app := newTestApp(t, &h, &sess)
	app.RequireStart()

	t.Cleanup(app.RequireStop)

	req := httptest.NewRequestWithContext(
		context.Background(), http.MethodGet, "/", nil)
	w := httptest.NewRecorder()

	s, err := sess.Get(req)
	require.NoError(t, err)

	sess.SetUser(s, "test-user-id", "testuser")

	err = sess.Save(req, w, s)
	require.NoError(t, err)

	req2 := httptest.NewRequestWithContext(
		context.Background(), http.MethodGet, "/", nil)

	for _, cookie := range w.Result().Cookies() {
		req2.AddCookie(cookie)
	}

	w2 := httptest.NewRecorder()
	h.HandleIndex().ServeHTTP(w2, req2)

	assert.Equal(t, http.StatusSeeOther, w2.Code)
	assert.Equal(
		t, "/hooks", w2.Header().Get("Location"),
	)
}

func TestSetSlackTargetSettings_AcceptsPublicURL(t *testing.T) {
	t.Parallel()

	var h *handlers.Handlers

	app := newTestApp(t, &h)
	app.RequireStart()

	t.Cleanup(app.RequireStop)

	const hookURL = "http://93.184.216.34/services/T00/B00/xxx"

	var target database.Target

	errMsg := h.SetSlackTargetSettingsForTest(t.Context(), &target, hookURL)

	assert.Empty(t, errMsg)
	assert.Equal(t, hookURL, target.URL)
}

func TestSetSlackTargetSettings_RejectsReservedURL(t *testing.T) {
	t.Parallel()

	var h *handlers.Handlers

	app := newTestApp(t, &h)
	app.RequireStart()

	t.Cleanup(app.RequireStop)

	var target database.Target

	errMsg := h.SetSlackTargetSettingsForTest(
		t.Context(), &target, "http://169.254.169.254/latest/meta-data/",
	)

	assert.Contains(t, errMsg, "Invalid target URL")
	assert.Empty(t, target.URL)
}

func TestRenderTemplate(t *testing.T) {
	t.Parallel()

	var h *handlers.Handlers

	app := newTestApp(t, &h)
	app.RequireStart()

	t.Cleanup(app.RequireStop)

	req := httptest.NewRequestWithContext(
		context.Background(), http.MethodGet, "/", nil)
	w := httptest.NewRecorder()

	data := map[string]any{"Version": "1.0.0"}

	h.RenderTemplateForTest(
		w, req, "nonexistent.html", data,
	)

	assert.Equal(
		t, http.StatusInternalServerError, w.Code,
	)
}

// errMidRender is the failure a test template raises partway through
// rendering.
var errMidRender = errors.New("deliberate mid-render failure")

// midRenderFailure is template data whose first method renders and
// whose second fails, so the template aborts after output has
// already been produced.
type midRenderFailure struct{}

// Prefix is the output a streaming renderer would flush before the
// failure below aborts the template.
func (midRenderFailure) Prefix() string { return partialPageMarker }

// Boom aborts template execution.
func (midRenderFailure) Boom() (string, error) {
	return "", errMidRender
}

// partialPageMarker is content the failing template emits before it
// aborts.
const partialPageMarker = "PARTIAL PAGE CONTENT"

// TestRenderTemplateMidRenderErrorSendsNoPartialBody proves the
// renderer does not commit output it cannot finish: a template that
// fails partway through must yield a 500 and a body carrying none of
// the content emitted before the failure. Against a renderer that
// executes straight into the ResponseWriter this fails on both
// counts, returning 200 with the prefix already flushed.
func TestRenderTemplateMidRenderErrorSendsNoPartialBody(t *testing.T) {
	t.Parallel()

	var h *handlers.Handlers

	app := newTestApp(t, &h)
	app.RequireStart()

	t.Cleanup(app.RequireStop)

	h.AddTemplateForTest("failing.html", template.Must(
		template.New("failing").Parse(
			`{{.Data.Prefix}}{{.Data.Boom}}TAIL`,
		),
	))

	req := httptest.NewRequestWithContext(
		context.Background(), http.MethodGet, "/", nil)
	w := httptest.NewRecorder()

	h.RenderTemplateForTest(
		w, req, "failing.html", midRenderFailure{},
	)

	assert.Equal(
		t, http.StatusInternalServerError, w.Code,
		"a failed render must report a 500",
	)
	assert.NotContains(
		t, w.Body.String(), partialPageMarker,
		"the response must carry no part of the aborted page",
	)
	assert.Contains(
		t, w.Body.String(), "500 Internal Server Error",
		"a failed render must answer with the error page",
	)
}

func TestSetDatabaseTargetSettings_Valid(t *testing.T) {
	t.Parallel()

	cases := []struct {
		expiry, rotation string
		wantExpiry       time.Duration
		wantRotation     string
	}{
		// Empty expiry and rotation: the keep-forever, one-file
		// default.
		{"", "", 0, rotationNone},
		{expiryNever, "", 0, rotationNone},
		{" 36h ", "", 36 * time.Hour, rotationNone},
		{"", rotationDaily, 0, rotationDaily},
		{"90m", rotationHourly, 90 * time.Minute, rotationHourly},
	}

	for _, tc := range cases {
		var target database.Target

		errMsg := handlers.SetDatabaseTargetSettingsForTest(
			&target, tc.expiry, tc.rotation,
		)

		assert.Empty(t, errMsg, tc)
		assert.Equal(t, tc.wantExpiry, target.ArchiveExpiry, tc)
		assert.Equal(t, tc.wantRotation, target.ArchiveRotation, tc)
	}
}

// TestSetDatabaseTargetSettings_RejectsBadExpiry pins each refusal's
// whole message, as the form shows it.
func TestSetDatabaseTargetSettings_RejectsBadExpiry(
	t *testing.T,
) {
	t.Parallel()

	cases := map[string]string{
		"nonsense": `Invalid archive expiry: expiry must be "never" or ` +
			`a Go duration such as "720h": time: invalid duration ` +
			`"nonsense"`,
		"7d": `Invalid archive expiry: expiry must be "never" or a Go ` +
			`duration such as "720h": time: unknown unit "d" in ` +
			`duration "7d"`,
		"-5h": `Invalid archive expiry: expiry must be a positive ` +
			`duration or "never": "-5h"`,
	}

	for bad, want := range cases {
		var target database.Target

		errMsg := handlers.SetDatabaseTargetSettingsForTest(
			&target, bad, "",
		)

		assert.Equal(t, want, errMsg, "expiry %q", bad)
	}
}

func TestSetDatabaseTargetSettings_RejectsBadRotation(
	t *testing.T,
) {
	t.Parallel()

	for _, bad := range []string{"weekly", "Daily", " none"} {
		var target database.Target

		errMsg := handlers.SetDatabaseTargetSettingsForTest(
			&target, "", bad,
		)

		assert.Equal(
			t,
			"Invalid archive rotation: rotation must be none, "+
				"monthly, daily or hourly: "+strconv.Quote(bad),
			errMsg,
		)
	}
}

// TestFormatArchiveExpiry covers the expiries the expiry choices do
// not: TestArchiveExpiryChoices shows the edit form starting on each
// choice. An expiry in whole hours is written in hours, and any other
// as Go writes it, which the form accepts back unchanged.
func TestFormatArchiveExpiry(t *testing.T) {
	t.Parallel()

	cases := map[time.Duration]string{
		0:                expiryNever,
		36 * time.Hour:   "36h",
		90 * time.Minute: "1h30m0s",
	}

	for expiry, want := range cases {
		assert.Equal(t, want, handlers.FormatArchiveExpiryForTest(expiry))
	}
}