package main

import (
	"database/sql"
	"fmt"
	"os/exec"
	"strconv"
	"strings"
)

type tableInfo struct {
	Name     string
	RowCount int64
}

// listTablesForDatabase returns the list of tables for a given DB file.
// Supports kind="sqlite" (uses database/sql + sqlite3 driver) and
// kind="duckdb" (uses python venv subprocess since go-duckdb is not linked
// in sqlite_api — it lives in the root module, not here).
func listTablesForDatabase(kind, path string) ([]tableInfo, error) {
	switch kind {
	case "sqlite":
		return listSQLiteTables(path)
	case "duckdb":
		return listDuckDBTablesViaCLI(path)
	default:
		return nil, fmt.Errorf("unsupported kind: %s", kind)
	}
}

func listSQLiteTables(path string) ([]tableInfo, error) {
	db, err := sql.Open("sqlite3", "file:"+path+"?mode=ro")
	if err != nil {
		return nil, err
	}
	defer db.Close()

	rows, err := db.Query(`
		SELECT name FROM sqlite_master
		WHERE type='table'
		  AND name NOT LIKE 'sqlite_%'
		  AND name != '_migrations'
		ORDER BY name`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []tableInfo
	for rows.Next() {
		var name string
		if err := rows.Scan(&name); err != nil {
			continue
		}
		var cnt int64
		row := db.QueryRow(`SELECT count(*) FROM "` + name + `"`)
		_ = row.Scan(&cnt)
		out = append(out, tableInfo{Name: name, RowCount: cnt})
	}
	return out, nil
}

func listDuckDBTablesViaCLI(path string) ([]tableInfo, error) {
	// Use the python venv's duckdb module to avoid linking go-duckdb.
	pyBin := "/home/lucas/fn_registry/python/.venv/bin/python3"
	script := fmt.Sprintf(
		`import duckdb,sys
c=duckdb.connect(%q, read_only=True)
for (name,) in c.execute("SELECT table_name FROM information_schema.tables WHERE table_schema='main' ORDER BY table_name").fetchall():
    cnt=c.execute(f'SELECT count(*) FROM "{name}"').fetchone()[0]
    print(f"{name}\t{cnt}")
`, path)
	cmd := exec.Command(pyBin, "-c", script)
	out, err := cmd.CombinedOutput()
	if err != nil {
		return nil, fmt.Errorf("duckdb via python: %w (output: %s)", err, string(out))
	}

	var result []tableInfo
	for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
		if line == "" {
			continue
		}
		parts := strings.SplitN(line, "\t", 2)
		if len(parts) != 2 {
			continue
		}
		cnt, _ := strconv.ParseInt(strings.TrimSpace(parts[1]), 10, 64)
		result = append(result, tableInfo{Name: parts[0], RowCount: cnt})
	}
	return result, nil
}