package tequat

import (
    "bufio"
    "bytes"
    "io"
)

func parseTextPlain(r io.Reader) (TQA, error) {
    var atoms []Atom
    buf := new(bytes.Buffer)

    var bufis int
    const (
        bufisNone = iota
        bufisText
        bufisQuote
    )

    flush := func() {
        defer func() {
            buf.Reset()
            bufis = bufisNone
        }()

        switch bufis {
        case bufisText:
            atoms = append(atoms, Text{buf.String()})
        case bufisQuote:
            atoms = append(atoms, Quote{buf.String()})
        default:
            if buf.Len() > 0 {
                panic("unreachable")
            }
        }
    }

    scanner := bufio.NewScanner(r)
    for scanner.Scan() {
        token := scanner.Bytes()

        is := bufisText
        if len(token) > 0 && token[0] == '>' {
            is = bufisQuote
            token = token[1:]
        }

        if bufis != is {
            flush()
        }
        bufis = is

        buf.Write(token)
        buf.WriteRune('\n')
    }
    flush()
    return TQA(atoms).Normalised(), scanner.Err()
}