package journal_test

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
	"sync"
	"testing"

	"git.golem15.com/golem15/sm-journal-plugin/controllers"
	"git.golem15.com/golem15/sm-journal-plugin/models"
)

// purgeTestToken is a 40-character purge token for the receiver.
const purgeTestToken = "purge-test-token-0123456789abcdefghijklm"

const purgeTestPath = "/api/__journal__/cache/purge"

// purgeRequest is one request the purge receiver got.
type purgeRequest struct {
	Method        string
	Path          string
	Authorization string
	ContentType   string
	Body          map[string]string
	// Seen is what the receiver's probe read from the database while the
	// request was in flight.
	Seen string
}

// purgeReceiver stands in for the host site's purge route on 127.0.0.1.
type purgeReceiver struct {
	srv    *httptest.Server
	mu     sync.Mutex
	got    []purgeRequest
	status int
	probe  func() string
}

func newPurgeReceiver(t *testing.T) *purgeReceiver {
	t.Helper()
	r := &purgeReceiver{status: http.StatusOK}
	r.srv = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		raw, _ := io.ReadAll(req.Body)
		var body map[string]string
		_ = json.Unmarshal(raw, &body)
		r.mu.Lock()
		probe, status := r.probe, r.status
		r.mu.Unlock()
		seen := ""
		if probe != nil {
			seen = probe()
		}
		r.mu.Lock()
		r.got = append(r.got, purgeRequest{
			Method:        req.Method,
			Path:          req.URL.Path,
			Authorization: req.Header.Get("Authorization"),
			ContentType:   req.Header.Get("Content-Type"),
			Body:          body,
			Seen:          seen,
		})
		r.mu.Unlock()
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(status)
		if status == http.StatusOK {
			_, _ = w.Write([]byte(`{"purged":3}`))
		}
	}))
	t.Cleanup(r.srv.Close)
	return r
}

// env returns the extra environment that points the Journal plugin at r.
func (r *purgeReceiver) env() []string {
	return []string{
		"SUMMER_GOLEM15__JOURNAL__SITE_CACHE__PURGE_URL=" + r.srv.URL + purgeTestPath,
		"SUMMER_GOLEM15__JOURNAL__SITE_CACHE__PURGE_TOKEN=" + purgeTestToken,
	}
}

// take returns the requests received so far and forgets them.
func (r *purgeReceiver) take() []purgeRequest {
	r.mu.Lock()
	defer r.mu.Unlock()
	got := r.got
	r.got = nil
	return got
}

func (r *purgeReceiver) setStatus(status int) {
	r.mu.Lock()
	r.status = status
	r.mu.Unlock()
}

func (r *purgeReceiver) setProbe(probe func() string) {
	r.mu.Lock()
	r.probe = probe
	r.mu.Unlock()
}

// expectOnePurge asserts exactly one contract request for kind and slug was
// received since the last take, and returns it.
func (r *purgeReceiver) expectOnePurge(t *testing.T, stage, kind, slug string) purgeRequest {
	t.Helper()
	got := r.take()
	if len(got) != 1 {
		t.Fatalf("%s: %d purge requests, want 1: %+v", stage, len(got), got)
	}
	req := got[0]
	if req.Method != http.MethodPost || req.Path != purgeTestPath {
		t.Fatalf("%s: purge request %s %s, want POST %s", stage, req.Method, req.Path, purgeTestPath)
	}
	if req.Authorization != "Bearer "+purgeTestToken {
		t.Fatalf("%s: Authorization = %q, want the bearer token", stage, req.Authorization)
	}
	if !strings.HasPrefix(req.ContentType, "application/json") {
		t.Fatalf("%s: Content-Type = %q, want application/json", stage, req.ContentType)
	}
	if req.Body["kind"] != kind || req.Body["slug"] != slug || len(req.Body) != 2 {
		t.Fatalf("%s: purge body = %#v, want kind %q and slug %q", stage, req.Body, kind, slug)
	}
	return req
}

// TestCategoriesAdminPurgesSiteCache proves every admin write of a category
// sends one authorized purge request with kind category after the save
// transaction commits, and a failed save sends none (G-16.2-2, D-19).
func TestCategoriesAdminPurgesSiteCache(t *testing.T) {
	recv := newPurgeReceiver(t)
	env := newPostsEnv(t, recv.env()...)
	token := env.admin(t, controllers.PermissionAccessCategories)

	// The probe reads the committed row through the pool while the purge
	// request is in flight: "<content>" or "missing".
	recv.setProbe(func() string {
		var cat models.Category
		if err := env.gdb.Where("slug = ?", "purge-news").Limit(1).Find(&cat).Error; err != nil {
			return "error: " + err.Error()
		}
		if cat.ID == 0 {
			return "missing"
		}
		if cat.Content == nil {
			return ""
		}
		return *cat.Content
	})

	rec := env.expect(t, http.StatusCreated, http.MethodPost, adminAPI(adminCategoriesPath), token, map[string]any{
		"name":    map[string]any{"en": "Purge news", "pl": "Wiadomości"},
		"slug":    map[string]any{"en": "purge-news", "pl": "wiadomosci"},
		"content": "<p>Before</p>\n",
	})
	id := adminCreatedID(t, rec)
	itemPath := adminAPI(fmt.Sprintf("%s/%d", adminCategoriesPath, id))
	if req := recv.expectOnePurge(t, "create", "category", "purge-news"); req.Seen != "<p>Before</p>\n" {
		t.Fatalf("create: the purge saw %q, want the committed row", req.Seen)
	}

	served := func(t *testing.T) map[string]json.RawMessage {
		t.Helper()
		rec := env.expect(t, http.StatusOK, http.MethodGet, itemPath, token, nil)
		var data map[string]json.RawMessage
		if err := json.Unmarshal(adminDecode(t, rec).Data, &data); err != nil {
			t.Fatal(err)
		}
		return data
	}

	t.Run("update", func(t *testing.T) {
		const edited = "<p>After the edit</p>\n"
		body := servedBody(served(t), "name", "slug")
		body["content"] = edited
		env.expect(t, http.StatusOK, http.MethodPut, itemPath, token, body)
		if req := recv.expectOnePurge(t, "update", "category", "purge-news"); req.Seen != edited {
			t.Fatalf("the purge saw content %q, want the committed %q (purge before commit)", req.Seen, edited)
		}
	})

	t.Run("a failed update sends none", func(t *testing.T) {
		body := servedBody(served(t), "slug")
		body["name"] = map[string]any{"en": "", "pl": ""}
		body["content"] = "<p>Refused</p>\n"
		if rec := env.call(t, http.MethodPut, itemPath, token, body); rec.Code != http.StatusUnprocessableEntity {
			t.Fatalf("update without a name = %d, want 422: %s", rec.Code, rec.Body.String())
		}
		if got := recv.take(); len(got) != 0 {
			t.Fatalf("a failed update sent %d purge requests: %+v", len(got), got)
		}
	})

	t.Run("delete", func(t *testing.T) {
		env.expect(t, http.StatusOK, http.MethodDelete, itemPath, token, nil)
		if req := recv.expectOnePurge(t, "delete", "category", "purge-news"); req.Seen != "missing" {
			t.Fatalf("the purge saw %q, want the row already deleted", req.Seen)
		}
	})
}

// TestPostsAdminPurgesSiteCache proves every admin write of a post sends one
// authorized purge request with kind post after the commit, that an
// untouched save still purges and keeps both content columns byte for byte
// (D-03), that a refused, failing or unreachable purge never changes the
// save response, and that a failed save sends none.
func TestPostsAdminPurgesSiteCache(t *testing.T) {
	recv := newPurgeReceiver(t)
	env := newPostsEnv(t, recv.env()...)
	token := env.admin(t, controllers.PermissionAccessPosts)

	recv.setProbe(func() string {
		var post models.Post
		if err := env.gdb.Where("slug = ?", "purge-post").Limit(1).Find(&post).Error; err != nil {
			return "error: " + err.Error()
		}
		if post.ID == 0 {
			return "missing"
		}
		return post.ContentHTML
	})

	rec := env.expect(t, http.StatusCreated, http.MethodPost, adminAPI(adminPostsPath), token, map[string]any{
		"title":   map[string]any{"en": "Purge post", "pl": "Wpis"},
		"slug":    map[string]any{"en": "purge-post", "pl": "wpis"},
		"content": map[string]any{"en": "<p>Before</p>"},
		"excerpt": map[string]any{"en": "Excerpt", "pl": "Wyjątek"},
	})
	id := adminCreatedID(t, rec)
	itemPath := adminAPI(fmt.Sprintf("%s/%d", adminPostsPath, id))
	if req := recv.expectOnePurge(t, "create", "post", "purge-post"); req.Seen != "<p>Before</p>" {
		t.Fatalf("create: the purge saw %q, want the committed row", req.Seen)
	}

	put := func(t *testing.T, content string) *httptest.ResponseRecorder {
		t.Helper()
		body := servedBody(servedForm(t, env, token, id), "title", "slug", "excerpt")
		body["content"] = map[string]any{"en": content}
		return env.call(t, http.MethodPut, itemPath, token, body)
	}
	stored := func(t *testing.T) models.Post {
		t.Helper()
		var post models.Post
		if err := env.gdb.First(&post, id).Error; err != nil {
			t.Fatal(err)
		}
		return post
	}

	t.Run("update", func(t *testing.T) {
		const edited = "<p>After the edit</p>"
		if rec := put(t, edited); rec.Code != http.StatusOK {
			t.Fatalf("update = %d: %s", rec.Code, rec.Body.String())
		}
		if req := recv.expectOnePurge(t, "update", "post", "purge-post"); req.Seen != edited {
			t.Fatalf("the purge saw content_html %q, want the committed %q (purge before commit)", req.Seen, edited)
		}
	})

	t.Run("an untouched update purges and keeps both columns", func(t *testing.T) {
		const imported = "\n<!-- imported -->\n<p onclick=\"x()\">Kept as stored</p>\n"
		const importedHTML = "<p>Rendered elsewhere</p>\n"
		if err := env.gdb.Model(&models.Post{}).Where("id = ?", id).Updates(map[string]any{"content": imported, "content_html": importedHTML}).Error; err != nil {
			t.Fatal(err)
		}
		served := servedForm(t, env, token, id)
		env.expect(t, http.StatusOK, http.MethodPut, itemPath, token, servedBody(served, "title", "slug", "excerpt", "content"))
		recv.expectOnePurge(t, "untouched update", "post", "purge-post")
		assertHostContent(t, env, id, "untouched update", imported, importedHTML)
	})

	t.Run("a failed save sends none", func(t *testing.T) {
		// The admin lacks access_publish: FormBeforeUpdate refuses inside
		// the save transaction.
		body := servedBody(servedForm(t, env, token, id), "title", "slug", "excerpt")
		body["published"] = true
		if rec := env.call(t, http.MethodPut, itemPath, token, body); rec.Code != http.StatusForbidden {
			t.Fatalf("publish without access_publish = %d, want 403: %s", rec.Code, rec.Body.String())
		}
		if got := recv.take(); len(got) != 0 {
			t.Fatalf("a failed save sent %d purge requests: %+v", len(got), got)
		}
	})

	t.Run("a failing purge never changes the save", func(t *testing.T) {
		recv.setStatus(http.StatusInternalServerError)
		defer recv.setStatus(http.StatusOK)
		const edited = "<p>Saved while the site answers 500</p>"
		if rec := put(t, edited); rec.Code != http.StatusOK {
			t.Fatalf("update with a failing purge = %d: %s", rec.Code, rec.Body.String())
		}
		recv.expectOnePurge(t, "failing purge", "post", "purge-post")
		if got := stored(t); got.Content != edited || got.ContentHTML != edited {
			t.Fatalf("stored = %q / %q, want %q", got.Content, got.ContentHTML, edited)
		}
	})

	t.Run("delete", func(t *testing.T) {
		spare := env.expect(t, http.StatusCreated, http.MethodPost, adminAPI(adminPostsPath), token, map[string]any{
			"title":   map[string]any{"en": "Spare"},
			"slug":    map[string]any{"en": "spare-post"},
			"content": map[string]any{"en": "<p>Spare</p>"},
		})
		spareID := adminCreatedID(t, spare)
		recv.expectOnePurge(t, "spare create", "post", "spare-post")
		env.expect(t, http.StatusOK, http.MethodDelete, adminAPI(fmt.Sprintf("%s/%d", adminPostsPath, spareID)), token, nil)
		recv.expectOnePurge(t, "delete", "post", "spare-post")
		var n int64
		if err := env.gdb.Model(&models.Post{}).Where("id = ?", spareID).Count(&n).Error; err != nil || n != 0 {
			t.Fatalf("spare post rows = %d (%v), want 0", n, err)
		}
	})

	// Last: closing the receiver ends its use for this env.
	t.Run("an unreachable site never changes the save", func(t *testing.T) {
		recv.srv.Close()
		const edited = "<p>Saved while nothing listens</p>"
		if rec := put(t, edited); rec.Code != http.StatusOK {
			t.Fatalf("update with no receiver = %d: %s", rec.Code, rec.Body.String())
		}
		if got := stored(t); got.Content != edited || got.ContentHTML != edited {
			t.Fatalf("stored = %q / %q, want %q", got.Content, got.ContentHTML, edited)
		}
		if got := recv.take(); len(got) != 0 {
			t.Fatalf("a closed receiver recorded %d requests", len(got))
		}
	})
}