package main
import (
	"encoding/json"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"runtime/debug"
	"strings"
)
type SQLCOutput struct {
	Catalog struct {
		Schemas []struct {
			Tables []struct {
				Doc string `json:"comment"`
				Rel struct {
					Name string `json:"name"`
				} `json:"rel"`
				Columns []struct {
					Name string `json:"name"`
					NotNull bool `json:"not_null"`
					Doc string `json:"comment"`
					Type struct {
						Name string `json:"name"`
					} `json:"type"`
				} `json:"columns"`
			} `json:"tables"`
		} `json:"schemas"`
	} `json:"catalog"`
}
func (doc SQLCOutput) WriteNotice(w io.Writer, input_name string) {
	info, _ := debug.ReadBuildInfo()
	module := info.Main.Path
	fmt.Fprintf(w, "Generated from %s by %s, do not edit\n\n", filepath.Base(input_name), module)
}
func (doc SQLCOutput) Markdown(w io.Writer) {
	tables := doc.Catalog.Schemas[0].Tables
	for _, table := range tables {
		fmt.Fprintf(w, "## Table `%s`\n\n%s\n\n|column|type|doc|\n|-|-|-|\n", table.Rel.Name, table.Doc)
		for _, column := range table.Columns {
			nullness := ""
			if column.NotNull {
				nullness = "NOT "
			}
			typename := strings.ToUpper(column.Type.Name)
			fmt.Fprintf(w, "|`%s`|`%s %sNULL`|%s\n", column.Name, typename, nullness, column.Doc)
		}
	}
}
func main() {
	if err := realMain(); err != nil {
		fmt.Fprintln(os.Stderr, err.Error())
		os.Exit(1)
	}
	os.Exit(0)
}
func realMain() error {
	if len(os.Args) != 2 {
		return fmt.Errorf("expect exactly 1 arg (path to SQLC generated JSON file)")
	}
	input_name := os.Args[1]
	output_name := strings.TrimSuffix(input_name, filepath.Ext(input_name)) + ".md"
	txt, err := os.ReadFile(input_name)
	if err != nil {
		return err
	}
	var parsed SQLCOutput
	if err := json.Unmarshal(txt, &parsed); err != nil {
		return fmt.Errorf("parsing JSON: %w", err)
	}
	output, err := os.Create(output_name)
	if err != nil {
		return fmt.Errorf("creating %s: %w", output_name, err)
	}
	defer output.Close()
	parsed.WriteNotice(output, input_name)
	parsed.Markdown(output)
	fmt.Printf("wrote to %s\n", output_name)
	return nil
}