// ingestd is the data on-ramp: CSV in (multipart form), Parquet out
// (to storaged), manifest registered (with catalogd). One round trip
// of HTTP, two service hops. The interesting glue lives in
// internal/ingestd/{schema,csv}.go and internal/catalogclient/;
// main.go just wires the route and threads the upstream URLs through.
package main

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"net/url"
	"os"
	"strings"
	"time"

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

	"git.agentview.dev/profit/golangLAKEHOUSE/internal/catalogclient"
	"git.agentview.dev/profit/golangLAKEHOUSE/internal/catalogd"
	"git.agentview.dev/profit/golangLAKEHOUSE/internal/ingestd"
	"git.agentview.dev/profit/golangLAKEHOUSE/internal/shared"
)

const (
	defaultMaxIngestBytes = 256 << 20 // floor; configurable via [ingestd].max_ingest_bytes
	// Per scrum C-DRIFT (Opus WARN): parquet keys are content-addressed
	// by schema fingerprint — datasets/<name>/<fp_hex>.parquet — so a
	// schema-drift ingest writes to a different key from the live one.
	// catalogd's 409 fires AFTER the PUT but the live parquet is
	// untouched (the new file is an orphan we GC in G2). Same-fingerprint
	// re-ingest still overwrites the same key, idempotent.
	parquetKeyPath = "datasets/%s/%s.parquet"
)

func main() {
	configPath := flag.String("config", "lakehouse.toml", "path to TOML config")
	flag.Parse()

	cfg, err := shared.LoadConfig(*configPath)
	if err != nil {
		slog.Error("config", "err", err)
		os.Exit(1)
	}
	if cfg.Ingestd.StoragedURL == "" || cfg.Ingestd.CatalogdURL == "" {
		slog.Error("config", "err", "ingestd.storaged_url and ingestd.catalogd_url are required")
		os.Exit(1)
	}

	maxBytes := cfg.Ingestd.MaxIngestBytes
	if maxBytes <= 0 {
		maxBytes = defaultMaxIngestBytes
	}

	h := &handlers{
		storagedURL: strings.TrimRight(cfg.Ingestd.StoragedURL, "/"),
		catalogd:    catalogclient.New(cfg.Ingestd.CatalogdURL),
		hc:          &http.Client{Timeout: 5 * time.Minute},
		maxBytes:    maxBytes,
	}

	if err := shared.Run("ingestd", cfg.Ingestd.Bind, h.register); err != nil {
		slog.Error("server", "err", err)
		os.Exit(1)
	}
}

type handlers struct {
	storagedURL string
	catalogd    *catalogclient.Client
	hc          *http.Client
	maxBytes    int64
}

func (h *handlers) register(r chi.Router) {
	r.Post("/ingest", h.handleIngest)
}

// ingestResponse is the 200 body shape — manifest as registered by
// catalogd plus a few stats from the parquet write. Existing flips
// true on idempotent re-ingest of the same name+fingerprint.
type ingestResponse struct {
	Manifest    *catalogd.Manifest `json:"manifest"`
	Existing    bool               `json:"existing"`
	RowCount    int64              `json:"row_count"`
	ParquetSize int64              `json:"parquet_size"`
	ParquetKey  string             `json:"parquet_key"`
}

func (h *handlers) handleIngest(w http.ResponseWriter, r *http.Request) {
	defer r.Body.Close()

	name := r.URL.Query().Get("name")
	if name == "" {
		http.Error(w, "name query param required", http.StatusBadRequest)
		return
	}

	// Multipart parse with a body cap that matches storaged's. We
	// don't stream straight from the form because the CSV needs to
	// be re-readable — the schema infer pre-reads N rows, and the
	// pqarrow writer needs all rows including those samples. We
	// take the simple path: the whole upload in memory, capped.
	r.Body = http.MaxBytesReader(w, r.Body, h.maxBytes)
	if err := r.ParseMultipartForm(64 << 20); err != nil {
		var maxErr *http.MaxBytesError
		if errors.As(err, &maxErr) || strings.Contains(err.Error(), "http: request body too large") {
			http.Error(w, "payload too large", http.StatusRequestEntityTooLarge)
			return
		}
		http.Error(w, "parse multipart: "+err.Error(), http.StatusBadRequest)
		return
	}
	file, _, err := r.FormFile("file")
	if err != nil {
		http.Error(w, "form file: "+err.Error(), http.StatusBadRequest)
		return
	}
	defer file.Close()

	// 1. CSV → schema → Parquet
	res, err := ingestd.IngestCSV(file, 0, 0)
	if err != nil {
		slog.Error("ingest csv", "name", name, "err", err)
		http.Error(w, "ingest csv: "+err.Error(), http.StatusBadRequest)
		return
	}

	// 2. PUT Parquet to storaged at a content-addressed path.
	fingerprint := res.Schema.Fingerprint()
	fpHex := strings.TrimPrefix(fingerprint, "sha256:")
	parquetKey := fmt.Sprintf(parquetKeyPath, name, fpHex)
	if err := h.putToStoraged(r.Context(), parquetKey, res.Parquet); err != nil {
		slog.Error("put parquet", "key", parquetKey, "err", err)
		http.Error(w, "put parquet: "+err.Error(), http.StatusBadGateway)
		return
	}

	// 3. Register with catalogd
	rc := res.RowCount
	regResp, err := h.catalogd.Register(r.Context(), &catalogclient.RegisterRequest{
		Name:              name,
		SchemaFingerprint: fingerprint,
		Objects:           []catalogd.Object{{Key: parquetKey, Size: int64(len(res.Parquet))}},
		RowCount:          &rc,
	})
	if errors.Is(err, catalogclient.ErrFingerprintConflict) {
		http.Error(w, err.Error(), http.StatusConflict)
		return
	}
	if err != nil {
		slog.Error("catalog register", "name", name, "err", err)
		http.Error(w, "catalog register: "+err.Error(), http.StatusBadGateway)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	_ = json.NewEncoder(w).Encode(ingestResponse{
		Manifest:    regResp.Manifest,
		Existing:    regResp.Existing,
		RowCount:    res.RowCount,
		ParquetSize: int64(len(res.Parquet)),
		ParquetKey:  parquetKey,
	})
}

// putToStoraged streams the parquet bytes to storaged at /storage/put/<key>.
// Mirrors the catalogd store_client shape — drain on error for keep-alive
// hygiene. Uses ContentLength up-front so storaged's 413 path fires
// deterministically on oversize.
func (h *handlers) putToStoraged(ctx context.Context, key string, body []byte) error {
	u := h.storagedURL + "/storage/put/" + escapeKeyPath(key)
	req, err := http.NewRequestWithContext(ctx, http.MethodPut, u, bytes.NewReader(body))
	if err != nil {
		return err
	}
	req.ContentLength = int64(len(body))
	resp, err := h.hc.Do(req)
	if err != nil {
		return err
	}
	defer drainAndClose(resp.Body)
	if resp.StatusCode != http.StatusOK {
		preview, _ := io.ReadAll(io.LimitReader(resp.Body, 256))
		return fmt.Errorf("put %s: status %d: %s", key, resp.StatusCode, string(preview))
	}
	return nil
}

func escapeKeyPath(key string) string {
	parts := strings.Split(key, "/")
	for i, p := range parts {
		parts[i] = url.PathEscape(p)
	}
	return strings.Join(parts, "/")
}

func drainAndClose(body io.ReadCloser) {
	_, _ = io.Copy(io.Discard, io.LimitReader(body, 64<<10))
	_ = body.Close()
}