// Package searchtest is a Typesense stand-in for the jz.bm tests: an
// httptest server that answers the collection, import, delete and search
// endpoints the beachcomber typesense engine calls, and an app configured to
// talk to it. Only tests import it.
package searchtest

import (
	"bufio"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"net/url"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"testing"

	"git.golem15.com/golem15/summercms/modules/backpack"
	_ "git.golem15.com/golem15/summercms/modules/beachcomber/typesense"
	"git.golem15.com/golem15/summercms/modules/compass"
)

// Index is the collection of the materials index.
const Index = "jz_bm_materials"

// HighlightStart and HighlightEnd are the highlight tags the typesense
// engine asks for (two private-use characters).
const (
	HighlightStart = ""
	HighlightEnd   = ""
)

// Hit is one search answer: a document id and, optionally, the snippet of
// one field with the matched words between HighlightStart and HighlightEnd.
type Hit struct {
	ID      string
	Field   string
	Snippet string
}

// Request is one request the stub received.
type Request struct {
	Method string
	Path   string
	Query  url.Values
}

// Stub stands in for a Typesense server with one collection.
type Stub struct {
	mu sync.Mutex
	// Hits answer every search, in rank order.
	Hits []Hit
	// Status, when set, answers every request with that code.
	Status int

	exists   bool
	requests []Request
	imported []map[string]any
	removed  []string
}

// ServeHTTP implements http.Handler.
func (s *Stub) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.requests = append(s.requests, Request{Method: r.Method, Path: r.URL.Path, Query: r.URL.Query()})
	if s.Status != 0 {
		w.WriteHeader(s.Status)
		_, _ = io.WriteString(w, `{"message":"stub failure"}`)
		return
	}
	coll := "/collections/" + Index
	switch {
	case r.Method == http.MethodGet && r.URL.Path == coll:
		if !s.exists {
			w.WriteHeader(http.StatusNotFound)
			_, _ = io.WriteString(w, `{"message":"Not Found"}`)
			return
		}
		_, _ = io.WriteString(w, `{}`)
	case r.Method == http.MethodPost && r.URL.Path == "/collections":
		s.exists = true
		w.WriteHeader(http.StatusCreated)
		_, _ = io.WriteString(w, `{}`)
	case r.Method == http.MethodDelete && r.URL.Path == coll:
		if !s.exists {
			w.WriteHeader(http.StatusNotFound)
			_, _ = io.WriteString(w, `{"message":"Not Found"}`)
			return
		}
		s.exists = false
		_, _ = io.WriteString(w, `{}`)
	case r.Method == http.MethodPost && r.URL.Path == coll+"/documents/import":
		s.exists = true
		sc := bufio.NewScanner(r.Body)
		sc.Buffer(make([]byte, 0, 64*1024), 16<<20)
		var answer []string
		for sc.Scan() {
			var doc map[string]any
			if err := json.Unmarshal(sc.Bytes(), &doc); err == nil {
				s.imported = append(s.imported, doc)
			}
			answer = append(answer, `{"success":true}`)
		}
		_, _ = io.WriteString(w, strings.Join(answer, "\n"))
	case r.Method == http.MethodDelete && strings.HasPrefix(r.URL.Path, coll+"/documents/"):
		s.removed = append(s.removed, strings.TrimPrefix(r.URL.Path, coll+"/documents/"))
		_, _ = io.WriteString(w, `{}`)
	case r.Method == http.MethodGet && r.URL.Path == coll+"/documents/search":
		hits := make([]string, 0, len(s.Hits))
		for _, h := range s.Hits {
			id, _ := json.Marshal(h.ID)
			highlights := "[]"
			if h.Field != "" {
				field, _ := json.Marshal(h.Field)
				snippet, _ := json.Marshal(h.Snippet)
				highlights = fmt.Sprintf(`[{"field":%s,"snippet":%s}]`, field, snippet)
			}
			hits = append(hits, fmt.Sprintf(`{"document":{"id":%s},"highlights":%s}`, id, highlights))
		}
		// found is deliberately larger than the hits, so a caller that
		// exposed it would show.
		_, _ = fmt.Fprintf(w, `{"found":%d,"hits":[%s]}`, len(s.Hits)+100, strings.Join(hits, ","))
	default:
		w.WriteHeader(http.StatusNotFound)
		_, _ = io.WriteString(w, `{"message":"Not Found"}`)
	}
}

// Requests returns the requests received so far.
func (s *Stub) Requests() []Request {
	s.mu.Lock()
	defer s.mu.Unlock()
	return append([]Request(nil), s.requests...)
}

// Searches returns the search requests received so far.
func (s *Stub) Searches() []Request {
	var out []Request
	for _, r := range s.Requests() {
		if r.Method == http.MethodGet && strings.HasSuffix(r.Path, "/documents/search") {
			out = append(out, r)
		}
	}
	return out
}

// Imported returns the documents upserted so far.
func (s *Stub) Imported() []map[string]any {
	s.mu.Lock()
	defer s.mu.Unlock()
	return append([]map[string]any(nil), s.imported...)
}

// Removed returns the document ids deleted so far.
func (s *Stub) Removed() []string {
	s.mu.Lock()
	defer s.mu.Unlock()
	return append([]string(nil), s.removed...)
}

// Start serves stub on an httptest server closed with the test, and returns
// the SUMMER_SEARCH__* environment that points the typesense engine at it
// with a test-only key.
func Start(t testing.TB, stub *Stub) []string {
	t.Helper()
	srv := httptest.NewServer(stub)
	t.Cleanup(srv.Close)
	u, err := url.Parse(srv.URL)
	if err != nil {
		t.Fatal(err)
	}
	return []string{
		"SUMMER_SEARCH__DRIVER=typesense",
		"SUMMER_SEARCH__TYPESENSE__API_KEY=test-only-typesense-key",
		"SUMMER_SEARCH__TYPESENSE__HOST=" + u.Hostname(),
		"SUMMER_SEARCH__TYPESENSE__PORT=" + u.Port(),
		"SUMMER_SEARCH__TYPESENSE__PROTOCOL=" + u.Scheme,
	}
}

// App returns a bare application whose config holds env (and SUMMER_ENV
// testing) and an empty config directory.
func App(t testing.TB, env ...string) *backpack.App {
	t.Helper()
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, "app.yaml"), []byte("name: jz-bm-test\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	cfg, err := compass.Open(compass.Options{Dir: dir, Environ: append([]string{"SUMMER_ENV=testing"}, env...)})
	if err != nil {
		t.Fatal(err)
	}
	return backpack.New(cfg)
}