package suggestions

import (
	"net/http"
	"path/filepath"
	"strings"
	"testing"

	"github.com/go-chi/chi/v5"

	"gitea.parodia.dev/drwily/petal/internal/auth"
	"gitea.parodia.dev/drwily/petal/internal/db"
	"gitea.parodia.dev/drwily/petal/internal/llm"
)

// The langpack decides what Petal says in the browser; users.pair_lang has to
// decide what the *model* says too, or a pt-PT writer gets a Mandarin gloss on
// an otherwise Portuguese screen. These tests follow the value from the column
// to the system prompt for each pass that names a language.
//
// This is the same failure mode the standing isolation rule guards against: the
// column is read in a query the handler already ran, so nothing fails loudly if
// the join is dropped — the prompt just quietly reverts to Mandarin.

// newPairServer seeds one writer on the given pair with a document of her own.
func newPairServer(t *testing.T, client llm.LLMClient, pairLang string) (http.Handler, string, *db.DB) {
	t.Helper()
	database, err := db.Open(filepath.Join(t.TempDir(), "pair.db"))
	if err != nil {
		t.Fatalf("open db: %v", err)
	}
	t.Cleanup(func() { database.Close() })

	const userID = "writer-pt"
	if _, err := database.Exec(
		`INSERT INTO users (id, email, display_name, pair_lang) VALUES (?, ?, ?, ?)`,
		userID, "w@example.com", "Writer", pairLang,
	); err != nil {
		t.Fatalf("seed user: %v", err)
	}

	var docID string
	if err := database.QueryRow(
		`INSERT INTO documents (user_id, content_text) VALUES (?, ?) RETURNING id`,
		userID, "The rain was strong yesterday.",
	).Scan(&docID); err != nil {
		t.Fatalf("seed doc: %v", err)
	}

	h := New(database, client)
	r := chi.NewRouter()
	r.Route("/docs", func(dr chi.Router) { h.RegisterDocRoutes(dr) })
	r.Mount("/suggestions", h.Routes())
	return auth.Middleware(auth.StaticResolver(userID))(r), docID, database
}

func TestCollocationPromptUsesTheWritersPair(t *testing.T) {
	client := &recordingClient{response: `{"suggestions":[]}`}
	srv, docID, _ := newPairServer(t, client, "pt-PT")

	rec := do(t, srv, http.MethodPost, "/docs/"+docID+"/collocation", "")
	if rec.Code != http.StatusOK {
		t.Fatalf("collocation: code=%d body=%s", rec.Code, rec.Body)
	}
	system := client.last.Messages[0].Content
	if !strings.Contains(system, "European Portuguese") {
		t.Fatalf("collocation prompt ignored pair_lang:\n%s", system)
	}
	if strings.Contains(system, "Simplified Chinese") {
		t.Fatalf("collocation prompt fell back to Mandarin:\n%s", system)
	}
}

func TestTranslatePromptUsesTheWritersPair(t *testing.T) {
	client := &recordingClient{response: "Chove muito."}
	srv, docID, database := newPairServer(t, client, "pt-PT")

	var sugID string
	if err := database.QueryRow(
		`INSERT INTO suggestions (doc_id, original, replacement, explanation, type, from_pos, to_pos)
		 VALUES (?, ?, ?, ?, ?, 0, 5) RETURNING id`,
		docID, "strong rain", "heavy rain", "Natives usually say heavy rain.", "collocation",
	).Scan(&sugID); err != nil {
		t.Fatalf("seed suggestion: %v", err)
	}

	rec := do(t, srv, http.MethodPost, "/suggestions/"+sugID+"/translate", "")
	if rec.Code != http.StatusOK {
		t.Fatalf("translate: code=%d body=%s", rec.Code, rec.Body)
	}
	system := client.last.Messages[0].Content
	if !strings.Contains(system, "European Portuguese") || strings.Contains(system, "Chinese") {
		t.Fatalf("translate prompt ignored pair_lang:\n%s", system)
	}
}

// A writer whose column still holds the default — every account today — must be
// answered exactly as before.
func TestDefaultPairIsUnchanged(t *testing.T) {
	client := &recordingClient{response: `{"suggestions":[]}`}
	srv, docID, _ := newPairServer(t, client, "zh")

	if rec := do(t, srv, http.MethodPost, "/docs/"+docID+"/collocation", ""); rec.Code != http.StatusOK {
		t.Fatalf("collocation: code=%d body=%s", rec.Code, rec.Body)
	}
	if system := client.last.Messages[0].Content; !strings.Contains(system, "Simplified Chinese (Mandarin) gloss") {
		t.Fatalf("zh writer no longer gets a Mandarin gloss:\n%s", system)
	}
}