package agent

import (
	"context"
	"iter"
	"strings"
	"testing"

	"github.com/VictorVargas/rony-llm-agent/pkg/llm"
	llmpersona "github.com/VictorVargas/rony-llm-agent/pkg/persona"

	"github.com/VictorVargas/rony-chat-bot/internal/portfolio"
)

// stubClient is a minimal llm.LLMClient that echoes the system prompt's
// last "###" block as a single chunk, then a usage chunk.
type stubClient struct {
	gotMessages []llm.Message
}

func (s *stubClient) Generate(_ context.Context, _ llm.CompletionRequest) (llm.CompletionResponse, error) {
	return llm.CompletionResponse{Content: "ok", Usage: llm.TokenUsage{InputTokens: 1, OutputTokens: 1}}, nil
}

func (s *stubClient) Stream(_ context.Context, req llm.CompletionRequest) iter.Seq2[llm.StreamChunk, error] {
	s.gotMessages = req.Messages
	return func(yield func(llm.StreamChunk, error) bool) {
		yield(llm.StreamChunk{Delta: "echo: " + req.Messages[len(req.Messages)-1].Content}, nil)
		yield(llm.StreamChunk{Delta: " [done]", FinishReason: "stop", Usage: llm.TokenUsage{InputTokens: 7, OutputTokens: 3}}, nil)
	}
}

func (s *stubClient) Name() string { return "stub" }
func (s *stubClient) Capabilities() llm.ProviderCapabilities {
	return llm.ProviderCapabilities{MaxContextWindow: 4096}
}

func TestRunnerStreamNoRAG(t *testing.T) {
	cli := &stubClient{}
	p := llmpersona.Persona{Name: "Tester", Tone: "concise", Language: "English"}
	r := New(cli, p, "test system prompt", nil, 5)

	var got strings.Builder
	for chunk, err := range r.Stream(context.Background(), []llm.Message{{Role: RoleUser, Content: "hi"}}) {
		if err != nil {
			t.Fatal(err)
		}
		got.WriteString(chunk.Delta)
	}
	want := "echo: hi [done]"
	if got.String() != want {
		t.Errorf("got %q, want %q", got.String(), want)
	}
}

func TestRunnerStreamWithRAG(t *testing.T) {
	cli := &stubClient{}
	p := llmpersona.Persona{Name: "Tester", Tone: "concise", Language: "English"}

	// Build a tiny on-disk store with one project.
	dir := t.TempDir()
	dbPath := dir + "/t.db"
	srcDir := dir + "/src"
	if err := writeFile(srcDir+"/proj.md", "# Demo\n\n## Tech stack\n- Go\n- SQLite database\n"); err != nil {
		t.Fatal(err)
	}
	store, err := portfolio.OpenStore(dbPath)
	if err != nil {
		t.Fatal(err)
	}
	defer store.Close()
	if _, _, err := store.Reindex(context.Background(), srcDir, portfolio.DefaultChunkerConfig()); err != nil {
		t.Fatal(err)
	}

	r := New(cli, p, "test system prompt", store, 5)
	for chunk, err := range r.Stream(context.Background(), []llm.Message{{Role: RoleUser, Content: "What database?"}}) {
		if err != nil {
			t.Fatal(err)
		}
		_ = chunk
	}
	// The system message the LLM saw should include the RAG context.
	if len(cli.gotMessages) == 0 {
		t.Fatal("LLM never received messages")
	}
	sys := cli.gotMessages[0].Content
	if !strings.Contains(sys, "Relevant context") {
		t.Errorf("system prompt missing RAG context block:\n%s", sys)
	}
	if !strings.Contains(sys, "SQLite") {
		t.Errorf("RAG context missing the SQLite content (got: %s)", sys)
	}
}

func writeFile(path, content string) error {
	if err := mkdirAll(path); err != nil {
		return err
	}
	return writeFileRaw(path, content)
}

// small helpers to avoid importing os/filepath in tests for a 2-call need
func mkdirAll(path string) error { return osMkdirAll(dirOf(path)) }
func dirOf(p string) string {
	for i := len(p) - 1; i >= 0; i-- {
		if p[i] == '/' {
			return p[:i]
		}
	}
	return "."
}