// ingestion/cmd/server/main.go
package main

import (
	"context"
	"fmt"
	"log/slog"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"

	chassisauth "gitea.d-ma.be/mathias/mcp-chassis/auth"

	"github.com/mathiasbq/hyperguild/ingestion/internal/api"
	"github.com/mathiasbq/hyperguild/ingestion/internal/llm"
	"github.com/mathiasbq/hyperguild/ingestion/internal/mcp"
	"github.com/mathiasbq/hyperguild/ingestion/internal/embed"
	"github.com/mathiasbq/hyperguild/ingestion/internal/metrics"
	"github.com/mathiasbq/hyperguild/ingestion/internal/oauth"
	"github.com/mathiasbq/hyperguild/ingestion/internal/pipeline"
	"github.com/mathiasbq/hyperguild/ingestion/internal/reranker"
	"github.com/mathiasbq/hyperguild/ingestion/internal/search"
	"github.com/mathiasbq/hyperguild/ingestion/internal/vectorstore"
	"github.com/mathiasbq/hyperguild/ingestion/internal/watcher"
)

// redactDSN parses a Postgres URL and replaces its password with `***`
// for safe inclusion in logs. Falls back to a non-leaking placeholder
// if parsing fails — we never log a raw DSN.
func redactDSN(dsn string) string {
	u, err := url.Parse(dsn)
	if err != nil || u.User == nil {
		return "postgres://***"
	}
	return u.Redacted()
}

// vectorAdapter bridges *vectorstore.PGStore (returns []vectorstore.Hit)
// to the search.VectorSearcher interface (which uses []search.VectorHit).
// Kept here, not in either package, so neither has to import the other.
type vectorAdapter struct{ s *vectorstore.PGStore }

func (a vectorAdapter) Search(ctx context.Context, q []float32, limit int) ([]search.VectorHit, error) {
	hits, err := a.s.Search(ctx, q, limit)
	if err != nil {
		return nil, err
	}
	out := make([]search.VectorHit, len(hits))
	for i, h := range hits {
		out[i] = search.VectorHit{Path: h.Path, Distance: h.Distance}
	}
	return out, nil
}

func envOr(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}

func envInt(key string, fallback int) int {
	if v := os.Getenv(key); v != "" {
		if n, err := strconv.Atoi(v); err == nil {
			return n
		}
	}
	return fallback
}

func main() {
	logger := slog.New(slog.NewJSONHandler(os.Stdout, nil))

	brainDir := envOr("INGEST_BRAIN_DIR", "../brain")
	port := envOr("INGEST_PORT", "3300")

	llmURL := envOr("INGEST_LLM_URL", "http://iguana:4000/v1")
	llmKey := os.Getenv("INGEST_LLM_KEY")
	llmModel := envOr("INGEST_LLM_MODEL", "koala/qwen35-9b-fast")
	llmTimeoutMins := envInt("INGEST_LLM_TIMEOUT", 15)
	chunkSize := envInt("INGEST_CHUNK_SIZE", 6000)
	watchInterval := envInt("INGEST_WATCH_INTERVAL", 30)

	llmClient := llm.New(llmURL, llmKey, llmModel, time.Duration(llmTimeoutMins)*time.Minute)

	pipelineCfg := pipeline.Config{
		Complete:  llmClient.Complete,
		ChunkSize: chunkSize,
	}

	h := api.NewHandler(brainDir, logger, pipelineCfg)

	var answerComplete pipeline.CompleteFunc
	if primaryURL := os.Getenv("BRAIN_LLM_PRIMARY_URL"); primaryURL != "" {
		primaryModel := envOr("BRAIN_LLM_PRIMARY_MODEL", "gemma4:31b")
		primaryKey := os.Getenv("BERGET_API_KEY")
		timeoutMS := envInt("BRAIN_LLM_TIMEOUT_MS", 10000)
		timeout := time.Duration(timeoutMS) * time.Millisecond

		primary := llm.New(primaryURL, primaryKey, primaryModel, timeout)
		router := &llm.Router{Primary: primary}

		if fallbackURL := os.Getenv("BRAIN_LLM_FALLBACK_URL"); fallbackURL != "" {
			fallbackModel := envOr("BRAIN_LLM_FALLBACK_MODEL", "gemma4:31b")
			router.Fallback = llm.New(fallbackURL, "", fallbackModel, timeout)
		}
		answerComplete = router.Complete
		logger.Info("brain answer LLM configured", "primary", primaryURL, "model", primaryModel)
	}

	mcpSrv := mcp.NewServer(brainDir, &pipelineCfg, llmClient.Complete, answerComplete)
	if rerankURL := os.Getenv("BRAIN_RERANKER_URL"); rerankURL != "" {
		rerankModel := envOr("BRAIN_RERANKER_MODEL", "dengcao/Qwen3-Reranker-0.6B:F16")
		mcpSrv = mcpSrv.WithReranker(reranker.New(rerankURL, rerankModel))
		logger.Info("brain reranker configured", "url", rerankURL, "model", rerankModel)
	}

	// Hybrid retrieval (pgvector + nomic-embed-text). Both env vars must
	// be set together for the path to wire on; otherwise BM25-only.
	var vectorStore *vectorstore.PGStore
	pgDSN := os.Getenv("BRAIN_PG_DSN")
	embedURL := os.Getenv("BRAIN_EMBED_URL")
	switch {
	case pgDSN != "" && embedURL != "":
		embedModel := envOr("BRAIN_EMBED_MODEL", "nomic-embed-text:latest")
		store, err := vectorstore.New(context.Background(), pgDSN)
		if err != nil {
			logger.Error("vector store init", "err", err)
			os.Exit(1)
		}
		if err := store.Init(context.Background()); err != nil {
			logger.Error("vector store migrate", "err", err)
			os.Exit(1)
		}
		vectorStore = store
		embedder := embed.New(embedURL, embedModel)
		mcpSrv = mcpSrv.WithHybridRetrieval(vectorAdapter{s: store}, embedder)
		h.WithEmbedSync(store, embedder)
		logger.Info("brain hybrid retrieval enabled",
			"pg", redactDSN(pgDSN),
			"embed_url", embedURL, "embed_model", embedModel)
	case pgDSN == "" && embedURL == "":
		// disabled — fine
	default:
		logger.Error("BRAIN_PG_DSN and BRAIN_EMBED_URL must be set together")
		os.Exit(1)
	}

	mcpToken := os.Getenv("BRAIN_MCP_TOKEN")
	if mcpToken == "" {
		logger.Error("BRAIN_MCP_TOKEN not set")
		os.Exit(1)
	}

	ctx := context.Background()
	if watchInterval > 0 {
		watcher.Start(ctx, watcher.Config{
			BrainDir: brainDir,
			Interval: time.Duration(watchInterval) * time.Second,
			Pipeline: pipelineCfg,
		})
	}
	if vectorStore != nil {
		embedSyncInterval := envInt("BRAIN_EMBED_SYNC_INTERVAL", 300)
		vectorstore.StartSync(ctx, brainDir, vectorStore,
			embed.New(os.Getenv("BRAIN_EMBED_URL"),
				envOr("BRAIN_EMBED_MODEL", "nomic-embed-text:latest")),
			time.Duration(embedSyncInterval)*time.Second)
		logger.Info("embed sync started", "interval_s", embedSyncInterval)
	}

	mux := http.NewServeMux()
	mux.HandleFunc("POST /query", h.Query)
	mux.HandleFunc("POST /write", h.Write)
	mux.HandleFunc("POST /index", h.Index)
	mux.HandleFunc("POST /ingest", h.Ingest)
	mux.HandleFunc("POST /ingest-path", h.IngestPath)
	mux.HandleFunc("POST /ingest-raw", h.IngestRaw)
	mux.HandleFunc("POST /backfill-refs", h.BackfillRefs)
	mux.HandleFunc("POST /backfill-embeddings", h.BackfillEmbeddings)
	mux.HandleFunc("GET /pass-rate", h.PassRate)
	jwtValidator, err := chassisauth.NewJWTValidator(ctx, os.Getenv("DEX_ISSUER_URL"), os.Getenv("MCP_AUDIENCE"))
	if err != nil {
		logger.Error("build jwt validator", "err", err)
		os.Exit(1)
	}
	if jwtValidator != nil {
		logger.Info("jwt auth enabled", "issuer", os.Getenv("DEX_ISSUER_URL"))
	}

	// Resource-metadata URL is only emitted on 401 when Dex OAuth is
	// configured. Static-Bearer-only deployments leave this empty so
	// clients never see an OAuth challenge.
	var resourceMetadataURL string
	if dexURL := os.Getenv("DEX_ISSUER_URL"); dexURL != "" {
		resourceURL := os.Getenv("MCP_RESOURCE_URL")
		mux.HandleFunc("GET /.well-known/oauth-protected-resource",
			chassisauth.ProtectedResourceHandler(resourceURL, dexURL))
		if resourceURL != "" {
			resourceMetadataURL = strings.TrimRight(resourceURL, "/") + "/.well-known/oauth-protected-resource"
		}
	}

	mux.Handle("/mcp", chassisauth.BearerMiddleware(mcpToken, jwtValidator, "brain", resourceMetadataURL, mcpSrv))

	// Opt-in OAuth 2.0 client_credentials flow for claude.ai's custom-MCP
	// integration UI, which has no static-Bearer field. Setting both
	// OAUTH_CLIENT_ID and OAUTH_CLIENT_SECRET enables the token exchange;
	// setting only one is misconfiguration → fail fast.
	oauthID := os.Getenv("OAUTH_CLIENT_ID")
	oauthSecret := os.Getenv("OAUTH_CLIENT_SECRET")
	switch {
	case oauthID != "" && oauthSecret != "":
		issuer := os.Getenv("MCP_RESOURCE_URL")
		if issuer == "" {
			logger.Error("OAUTH_CLIENT_ID/SECRET set but MCP_RESOURCE_URL is empty; cannot derive issuer")
			os.Exit(1)
		}
		mux.HandleFunc("GET /.well-known/oauth-authorization-server",
			oauth.MetadataHandler(issuer))
		mux.HandleFunc("POST /oauth/token", oauth.TokenHandler(oauth.TokenConfig{
			ClientID:     oauthID,
			ClientSecret: oauthSecret,
			AccessToken:  mcpToken,
		}))
		logger.Info("oauth client_credentials enabled", "issuer", strings.TrimRight(issuer, "/"))
	case oauthID == "" && oauthSecret == "":
		// disabled — that's fine
	default:
		logger.Error("OAUTH_CLIENT_ID and OAUTH_CLIENT_SECRET must be set together")
		os.Exit(1)
	}

	// /metrics — unauthenticated Prometheus endpoint. kube-prometheus-stack
	// scrapes it via the ServiceMonitor in k3s/apps/supervisor/. The metrics
	// middleware below wraps every other registered handler so it observes
	// real request latency. /metrics itself is excluded from its own
	// observation by registering it on the outer mux (post-wrap).
	reg := metrics.New()
	mux.HandleFunc("GET /metrics", reg.Handler())
	logger.Info("metrics endpoint registered", "path", "/metrics")

	addr := ":" + port
	watchIntervalLog := "disabled"
	if watchInterval > 0 {
		watchIntervalLog = fmt.Sprintf("%ds", watchInterval)
	}
	logger.Info("ingestion server starting",
		"addr", addr,
		"brain_dir", brainDir,
		"llm_url", llmURL,
		"llm_model", llmModel,
		"chunk_size", chunkSize,
		"watch_interval", watchIntervalLog,
		"mcp_enabled", true,
	)
	if err := http.ListenAndServe(addr, reg.Middleware(mux)); err != nil {
		logger.Error("server stopped", "err", err)
		os.Exit(1)
	}
}