// setup.go — `lem setup --data` hydrates cold JSONL.zst into warm DuckDB + hot InfluxDB.
package lem

import (
	"bufio"
	"encoding/json"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"strings"
)

// SetupOpts holds configuration for the setup --data command.
type SetupOpts struct {
	Root       string // LEM repo root (defaults to ".")
	DB         string // DuckDB path (defaults to LEM_DB env, then ./lem.duckdb)
	Influx     string // InfluxDB URL (empty = default)
	InfluxDB   string // InfluxDB database name (empty = default)
	SkipInflux bool   // Skip InfluxDB backfill
}

// RunSetup hydrates cold storage (JSONL.zst) into warm (DuckDB) and hot (InfluxDB).
func RunSetup(cfg SetupOpts) error {
	root := cfg.Root
	if root == "" {
		root = "."
	}

	dbPath := cfg.DB
	if dbPath == "" {
		dbPath = os.Getenv("LEM_DB")
	}
	if dbPath == "" {
		dbPath = filepath.Join(root, "lem.duckdb")
	}

	log.Printf("hydrating cold storage → %s", dbPath)

	db, err := OpenDBReadWrite(dbPath)
	if err != nil {
		return fmt.Errorf("open db: %w", err)
	}
	defer db.Close()

	// Create tables if they don't exist.
	if err := ensureSetupTables(db); err != nil {
		return fmt.Errorf("create tables: %w", err)
	}

	trainingDir := filepath.Join(root, "training")
	totals := make(map[string]int)

	// -- 1. Training examples from JSONL.zst --
	fmt.Println("  Hydrating training examples...")
	trainingTotal := 0
	walkZstFiles(trainingDir, func(zstPath string) error {
		rel, _ := filepath.Rel(trainingDir, zstPath)
		// Skip seeds (they're structured differently)
		if strings.HasPrefix(rel, "seeds/") || strings.HasPrefix(rel, "seeds"+string(filepath.Separator)) {
			return nil
		}

		source := strings.TrimSuffix(rel, ".jsonl.zst")
		split := "train"
		if strings.Contains(rel, "valid") {
			split = "valid"
		} else if strings.Contains(rel, "test") {
			split = "test"
		}

		n, err := hydrateTrainingFromZst(db, zstPath, source, split)
		if err != nil {
			log.Printf("  WARNING: %s: %v", rel, err)
			return nil
		}
		if n > 0 {
			trainingTotal += n
			log.Printf("  %s: %d examples", rel, n)
		}
		return nil
	})
	totals["training_examples"] = trainingTotal

	// -- 2. Seeds from JSONL.zst --
	fmt.Println("  Hydrating seeds...")
	seedsDir := filepath.Join(trainingDir, "seeds")
	seedTotal := 0
	if _, err := os.Stat(seedsDir); err == nil {
		seedTotal = importSeeds(db, seedsDir)
	}
	// Also try .zst seed files
	if _, err := os.Stat(seedsDir); err == nil {
		walkZstFiles(seedsDir, func(zstPath string) error {
			tmpFile, err := decompressToTemp(zstPath)
			if err != nil {
				log.Printf("  WARNING: decompress %s: %v", zstPath, err)
				return nil
			}
			defer os.Remove(tmpFile)

			// Seeds are JSONL format — import as seeds
			n := importSeedsFromJSONL(db, tmpFile, zstPath)
			seedTotal += n
			return nil
		})
	}
	totals["seeds"] = seedTotal

	// -- 3. Probes from JSON files --
	fmt.Println("  Hydrating probes...")
	probeTotal := 0
	probesCfg, cfgErr := LoadProbesConfig(root)
	if cfgErr == nil {
		for setName, set := range probesCfg.Sets {
			phase := 0
			if set.Phase != nil {
				phase = *set.Phase
			}
			for _, f := range set.Files {
				probePath := filepath.Join(root, "training", "lem", f)
				n, err := hydrateProbes(db, probePath, phase)
				if err != nil {
					log.Printf("  WARNING: probes %s/%s: %v", setName, f, err)
					continue
				}
				probeTotal += n
			}
		}
	}
	totals["probes"] = probeTotal

	// -- 4. InfluxDB backfill --
	if !cfg.SkipInflux {
		fmt.Println("  Backfilling InfluxDB...")
		influx := NewInfluxClient(cfg.Influx, cfg.InfluxDB)
		backfilled := backfillInflux(db, influx)
		fmt.Printf("  influx: %d points written\n", backfilled)
	}

	// -- Summary --
	fmt.Printf("\n%s\n", strings.Repeat("=", 50))
	fmt.Println("LEM Data Hydration Complete")
	fmt.Println(strings.Repeat("=", 50))
	grandTotal := 0
	for table, count := range totals {
		fmt.Printf("  %-25s %8d\n", table, count)
		grandTotal += count
	}
	fmt.Printf("  %s\n", strings.Repeat("-", 35))
	fmt.Printf("  %-25s %8d\n", "TOTAL", grandTotal)
	fmt.Printf("\nDatabase: %s\n", dbPath)
	return nil
}

// ensureSetupTables creates tables if they don't exist.
func ensureSetupTables(db *DB) error {
	tables := []string{
		`CREATE TABLE IF NOT EXISTS training_examples (
			source VARCHAR, split VARCHAR, prompt TEXT, response TEXT,
			num_turns INT, full_messages TEXT, char_count INT
		)`,
		`CREATE TABLE IF NOT EXISTS seeds (
			source_file VARCHAR, region VARCHAR, seed_id VARCHAR, domain VARCHAR, prompt TEXT
		)`,
		`CREATE TABLE IF NOT EXISTS probes (
			id TEXT, domain TEXT, prompt TEXT, phase INTEGER, source_file TEXT
		)`,
		`CREATE TABLE IF NOT EXISTS distill_results (
			probe_id TEXT, model TEXT, phase INTEGER,
			prompt TEXT, response TEXT, source_file TEXT,
			imported_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
		)`,
	}
	for _, ddl := range tables {
		if _, err := db.conn.Exec(ddl); err != nil {
			return fmt.Errorf("exec DDL: %w", err)
		}
	}
	return nil
}

// hydrateTrainingFromZst decompresses a .jsonl.zst file and imports chat-format
// training examples into DuckDB. Returns the number of rows imported.
func hydrateTrainingFromZst(db *DB, zstPath, source, split string) (int, error) {
	tmpFile, err := decompressToTemp(zstPath)
	if err != nil {
		return 0, err
	}
	defer os.Remove(tmpFile)

	// Ensure table exists before importing
	ensureSetupTables(db)

	return importTrainingFile(db, tmpFile, source, split), nil
}

// decompressToTemp decompresses a .zst file to a temporary file, returning the path.
func decompressToTemp(zstPath string) (string, error) {
	tmp, err := os.CreateTemp("", "lem-hydrate-*.jsonl")
	if err != nil {
		return "", fmt.Errorf("create temp: %w", err)
	}
	tmpPath := tmp.Name()
	tmp.Close()

	if err := decompressZstd(zstPath, tmpPath); err != nil {
		os.Remove(tmpPath)
		return "", err
	}
	return tmpPath, nil
}

// hydrateProbes reads a JSON probe file and inserts into the probes table.
func hydrateProbes(db *DB, path string, phase int) (int, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return 0, fmt.Errorf("read %s: %w", path, err)
	}

	// Ensure table exists
	ensureSetupTables(db)

	var probes []struct {
		ID     string `json:"id"`
		Domain string `json:"domain"`
		Prompt string `json:"prompt"`
	}
	if err := json.Unmarshal(data, &probes); err != nil {
		return 0, fmt.Errorf("parse %s: %w", filepath.Base(path), err)
	}

	rel := filepath.Base(path)
	count := 0
	for _, p := range probes {
		if _, err := db.conn.Exec(
			"INSERT INTO probes VALUES (?, ?, ?, ?, ?)",
			p.ID, p.Domain, p.Prompt, phase, rel,
		); err != nil {
			log.Printf("  WARNING: insert probe %s: %v", p.ID, err)
			continue
		}
		count++
	}
	return count, nil
}

// importSeedsFromJSONL imports seed data from a decompressed JSONL file.
func importSeedsFromJSONL(db *DB, path, sourcePath string) int {
	f, err := os.Open(path)
	if err != nil {
		return 0
	}
	defer f.Close()

	rel := filepath.Base(sourcePath)
	count := 0
	scanner := bufio.NewScanner(f)
	scanner.Buffer(make([]byte, 1024*1024), 1024*1024)

	for scanner.Scan() {
		var rec map[string]any
		if err := json.Unmarshal(scanner.Bytes(), &rec); err != nil {
			continue
		}
		prompt := strOrEmpty(rec, "prompt")
		if prompt == "" {
			prompt = strOrEmpty(rec, "text")
		}
		if prompt == "" {
			continue
		}
		if _, err := db.conn.Exec("INSERT INTO seeds VALUES (?, ?, ?, ?, ?)",
			rel, strOrEmpty(rec, "region"),
			strOrEmpty(rec, "seed_id"), strOrEmpty(rec, "domain"),
			prompt,
		); err != nil {
			continue
		}
		count++
	}
	return count
}

// backfillInflux writes aggregate stats from DuckDB to InfluxDB.
// Best-effort — returns count of points written.
func backfillInflux(db *DB, influx *InfluxClient) int {
	count := 0

	// Training examples summary
	rows, err := db.QueryRows("SELECT source, split, COUNT(*) AS n, SUM(char_count) AS chars FROM training_examples GROUP BY source, split")
	if err == nil {
		var lines []string
		for _, row := range rows {
			source := fmt.Sprintf("%v", row["source"])
			split := fmt.Sprintf("%v", row["split"])
			n := row["n"]
			chars := row["chars"]
			line := fmt.Sprintf("training_hydration,source=%s,split=%s examples=%vi,chars=%vi",
				escapeLp(source), escapeLp(split), n, chars)
			lines = append(lines, line)
		}
		if len(lines) > 0 {
			if err := influx.WriteLp(lines); err != nil {
				log.Printf("  influx training stats: %v", err)
			} else {
				count += len(lines)
			}
		}
	}

	// Probes summary
	probeRows, err := db.QueryRows("SELECT phase, COUNT(*) AS n FROM probes GROUP BY phase ORDER BY phase")
	if err == nil {
		var lines []string
		for _, row := range probeRows {
			phase := fmt.Sprintf("%v", row["phase"])
			n := row["n"]
			line := fmt.Sprintf("probe_hydration,phase=%s count=%vi", phase, n)
			lines = append(lines, line)
		}
		if len(lines) > 0 {
			if err := influx.WriteLp(lines); err != nil {
				log.Printf("  influx probe stats: %v", err)
			} else {
				count += len(lines)
			}
		}
	}

	return count
}