// Copyright (c) 2019-2024 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module csv

import strings

struct Writer {
    use_crlf  bool
    delimiter u8
mut:
    sb strings.Builder
}

@[params]
pub struct WriterConfig {
pub:
    use_crlf  bool
    delimiter u8 = `,`
}

// new_writer returns a reference to a Writer
pub fn new_writer(config WriterConfig) &Writer {
    return &Writer{
        sb:        strings.new_builder(200)
        use_crlf:  config.use_crlf
        delimiter: config.delimiter
    }
}

// write writes a single record
pub fn (mut w Writer) write(record []string) !bool {
    if !valid_delim(w.delimiter) {
        return &InvalidDelimiterError{}
    }
    le := if w.use_crlf { '\r\n' } else { '\n' }
    for n, field_ in record {
        mut field := field_
        if n > 0 {
            w.sb.write_string(w.delimiter.ascii_str())
        }
        if !w.field_needs_quotes(field) {
            w.sb.write_string(field)
            continue
        }
        w.sb.write_string('"')
        for field.len > 0 {
            mut i := field.index_any('"\r\n')
            if i < 0 {
                i = field.len
            }
            w.sb.write_string(field[..i])
            field = field[i..]
            if field.len > 0 {
                z := field[0]
                match z {
                    `"` { w.sb.write_string('""') }
                    `\r`, `\n` { w.sb.write_string(le) }
                    else {}
                }

                field = field[1..]
            }
        }
        w.sb.write_string('"')
    }
    w.sb.write_string(le)
    return true
}

// Once we have multi dimensional array
// pub fn (w &Writer) write_all(records [][]string) {
//     for _, record in records {
//         w.write(record)
//     }
// }
fn (w &Writer) field_needs_quotes(field string) bool {
    if field == '' {
        return false
    }
    if field.contains(w.delimiter.ascii_str()) || field.index_any('"\r\n') != -1 {
        return true
    }
    return false
}

// str returns the writer contents
pub fn (mut w Writer) str() string {
    return w.sb.str()
}