// Package markdownw implements writers for Markdown.
package markdownw

import (
	"bytes"
	"encoding/base64"
	"fmt"
	"html"
	"io"
	"strconv"
	"strings"
	"time"

	"github.com/neilotoole/sq/libsq/sqlz"
	"github.com/neilotoole/sq/libsq/stringz"
)

// RecordWriter implements output.RecordWriter.
type RecordWriter struct {
	recMeta sqlz.RecordMeta
	out     io.Writer
	buf     *bytes.Buffer
}

// NewRecordWriter returns a writer instance.
func NewRecordWriter(out io.Writer) *RecordWriter {
	return &RecordWriter{out: out}
}

// Open implements output.RecordWriter.
func (w *RecordWriter) Open(recMeta sqlz.RecordMeta) error {
	w.recMeta = recMeta
	w.buf = &bytes.Buffer{}

	// Write the header
	for i, field := range recMeta {
		w.buf.WriteString("| ")
		w.buf.WriteString(field.Name() + " ")

		if i == len(recMeta)-1 {
			w.buf.WriteString("|\n")
		}
	}

	// Write the header separator row
	for i := range recMeta {
		w.buf.WriteString("| --- ")

		if i == len(recMeta)-1 {
			w.buf.WriteString("|\n")
		}
	}

	return nil
}

// Flush implements output.RecordWriter.
func (w *RecordWriter) Flush() error {
	_, err := w.buf.WriteTo(w.out) // resets buf
	return err
}

// Close implements output.RecordWriter.
func (w *RecordWriter) Close() error {
	return w.Flush()
}

func (w *RecordWriter) writeRecord(rec sqlz.Record) error {
	var s string
	for i, field := range rec {
		w.buf.WriteString("| ")

		switch val := field.(type) {
		default:
			// should never happen
			s = escapeMarkdown(fmt.Sprintf("%v", val))

		case nil:
			// nil is rendered as empty string, which this cell already is
		case *int64:
			s = strconv.FormatInt(*val, 10)
		case *string:
			s = escapeMarkdown(*val)
		case *bool:
			s = strconv.FormatBool(*val)
		case *float64:
			s = stringz.FormatFloat(*val)
		case *[]byte:
			s = base64.StdEncoding.EncodeToString(*val)
		case *time.Time:
			switch w.recMeta[i].Kind() {
			default:
				s = val.Format(stringz.DatetimeFormat)
			case sqlz.KindTime:
				s = val.Format(stringz.TimeFormat)
			case sqlz.KindDate:
				s = val.Format(stringz.DateFormat)
			}
		}

		w.buf.WriteString(s + " ")
	}

	w.buf.WriteString("|\n")
	return nil
}

// WriteRecords implements output.RecordWriter.
func (w *RecordWriter) WriteRecords(recs []sqlz.Record) error {
	var err error
	for _, rec := range recs {
		err = w.writeRecord(rec)
		if err != nil {
			return err
		}
	}

	return nil
}

// escapeMarkdown is quick effort at escaping markdown
// table cell text. It is not at all tested. Replace this
// function with a real library call at the earliest opportunity.
func escapeMarkdown(s string) string {
	s = html.EscapeString(s)
	s = strings.Replace(s, "|", "|", -1)
	s = strings.Replace(s, "\r\n", "<br/>", -1)
	s = strings.Replace(s, "\n", "<br/>", -1)
	return s
}