package xvdoc

import (
	"encoding/json"
)

type Cell interface {
	Val() interface{}
	Type() string
	Styles() []string
}

type CellConstructor func(*json.Decoder, json.Token) (Cell, error)

var (
	cellConstructors []CellConstructor
)

func AppendCellConstructor(constructor CellConstructor) {
	cellConstructors = append(cellConstructors, constructor)
}

func init() {
	cellConstructors = []CellConstructor{
		constructorString,
		constructorNumber,
		constructorObject,
	}
}

func parseCell(dec *json.Decoder, t json.Token) (cell Cell, err error) {
	for _, constructor := range cellConstructors {
		if cell, err = constructor(dec, t); cell != nil || err != nil {
			return
		}
	}
	return
}

func parseCells(dec *json.Decoder) (res []Cell, err error) {
	var (
		t    json.Token
		cell Cell
	)
	if t, err = dec.Token(); err == nil {
		if _, check := t.(json.Delim); check && t == json.Delim('[') {
			for err == nil {
				if t, err = dec.Token(); err == nil {
					if _, check := t.(json.Delim); check && t == json.Delim(']') {
						return
					}
				}
				if cell, err = parseCell(dec, t); err == nil && cell != nil {
					res = append(res, cell)
				}
			}
		} else {
			if cell, err = parseCell(dec, t); err == nil && cell != nil {
				res = []Cell{cell}
			}
		}
	}
	return
}