var wrap = require('wordwrap'),
 align = {
 right: require('right-align'),
 center: require('center-align')
 },
 top = 0,
 right = 1,
 bottom = 2,
 left = 3

function UI (opts) {
 this.width = opts.width
 this.wrap = opts.wrap
 this.rows = []
}

UI.prototype.span = function () {
 var cols = this.div.apply(this, arguments)
 cols.span = true
}

UI.prototype.div = function () {
 if (arguments.length === 0) this.div('')
 if (this.wrap && this._shouldApplyLayoutDSL.apply(this, arguments)) {
 return this._applyLayoutDSL(arguments[0])
 }

 var cols = []

 for (var i = 0, arg; (arg = arguments[i]) !== undefined; i++) {
 if (typeof arg === 'string') cols.push(this._colFromString(arg))
 else cols.push(arg)
 }

 this.rows.push(cols)
 return cols
}

UI.prototype._shouldApplyLayoutDSL = function () {
 return arguments.length === 1 && typeof arguments[0] === 'string' &&
 /[\t\n]/.test(arguments[0])
}

UI.prototype._applyLayoutDSL = function (str) {
 var _this = this,
 rows = str.split('\n'),
 leftColumnWidth = 0

 // simple heuristic for layout, make sure the
 // second column lines up along the left-hand.
 // don't allow the first column to take up more
 // than 50% of the screen.
 rows.forEach(function (row) {
 var columns = row.split('\t')
 if (columns.length > 1 && columns[0].length > leftColumnWidth) {
 leftColumnWidth = Math.min(
 Math.floor(_this.width * 0.5),
 columns[0].length
 )
 }
 })

 // generate a table:
 // replacing ' ' with padding calculations.
 // using the algorithmically generated width.
 rows.forEach(function (row) {
 var columns = row.split('\t')
 _this.div.apply(_this, columns.map(function (r, i) {
 return {
 text: r.trim(),
 padding: [0, r.match(/\s*$/)[0].length, 0, r.match(/^\s*/)[0].length],
 width: (i === 0 && columns.length > 1) ? leftColumnWidth : undefined
 }
 }))
 })

 return this.rows[this.rows.length - 1]
}

UI.prototype._colFromString = function (str) {
 return {
 text: str
 }
}

UI.prototype.toString = function () {
 var _this = this,
 lines = []

 _this.rows.forEach(function (row, i) {
 _this.rowToString(row, lines)
 })

 // don't display any lines with the
 // hidden flag set.
 lines = lines.filter(function (line) {
 return !line.hidden
 })

 return lines.map(function (line) {
 return line.text
 }).join('\n')
}

UI.prototype.rowToString = function (row, lines) {
 var _this = this,
 paddingLeft,
 rrows = this._rasterize(row),
 str = '',
 ts,
 width,
 wrapWidth

 rrows.forEach(function (rrow, r) {
 str = ''
 rrow.forEach(function (col, c) {
 ts = '' // temporary string used during alignment/padding.
 width = row[c].width // the width with padding.
 wrapWidth = _this._negatePadding(row[c]) // the width without padding.

 for (var i = 0; i < Math.max(wrapWidth, col.length); i++) {
 ts += col.charAt(i) || ''
 }

 // align the string within its column.
 if (row[c].align && row[c].align !== 'left' && _this.wrap) {
 ts = align[row[c].align](ts.trim() + '\n' + new Array(wrapWidth + 1).join(''))
 .split('\n')[0]
 if (ts.length < wrapWidth) ts += new Array(width - ts.length).join('')
 }

 // add left/right padding and print string.
 paddingLeft = (row[c].padding || [0, 0, 0, 0])[left]
 if (paddingLeft) str += new Array(row[c].padding[left] + 1).join('')
 str += ts
 if (row[c].padding && row[c].padding[right]) str += new Array(row[c].padding[right] + 1).join('')

 // if prior row is span, try to render the
 // current row on the prior line.
 if (r === 0 && lines.length > 0) {
 str = _this._renderInline(str, lines[lines.length - 1], paddingLeft)
 }
 })

 // remove trailing whitespace.
 lines.push({
 text: str.replace(/ +$/, ''),
 span: row.span
 })
 })

 return lines
}

// if the full 'source' can render in
// the target line, do so.
UI.prototype._renderInline = function (source, previousLine, paddingLeft) {
 var target = previousLine.text,
 str = ''

 if (!previousLine.span) return source

 // if we're not applying wrapping logic,
 // just always append to the span.
 if (!this.wrap) {
 previousLine.hidden = true
 return target + source
 }

 for (var i = 0, tc, sc; i < Math.max(source.length, target.length); i++) {
 tc = target.charAt(i) || ''
 sc = source.charAt(i) || ''
 // we tried to overwrite a character in the other string.
 if (tc !== '' && sc !== '') return source
 // there is not enough whitespace to maintain padding.
 if (sc !== '' && i < paddingLeft + target.length) return source
 // :thumbsup:
 if (tc === '') str += sc
 else str += tc
 }

 previousLine.hidden = true

 return str
}

UI.prototype._rasterize = function (row) {
 var _this = this,
 i,
 rrow,
 rrows = [],
 widths = this._columnWidths(row),
 wrapped

 // word wrap all columns, and create
 // a data-structure that is easy to rasterize.
 row.forEach(function (col, c) {
 // leave room for left and right padding.
 col.width = widths[c]
 if (_this.wrap) wrapped = wrap.hard(_this._negatePadding(col))(col.text).split('\n')
 else wrapped = col.text.split('\n')

 // add top and bottom padding.
 if (col.padding) {
 for (i = 0; i < (col.padding[top] || 0); i++) wrapped.unshift('')
 for (i = 0; i < (col.padding[bottom] || 0); i++) wrapped.push('')
 }

 wrapped.forEach(function (str, r) {
 if (!rrows[r]) rrows.push([])

 rrow = rrows[r]

 for (var i = 0; i < c; i++) {
 if (rrow[i] === undefined) rrow.push('')
 }
 rrow.push(str)
 })
 })

 return rrows
}

UI.prototype._negatePadding = function (col) {
 var wrapWidth = col.width
 if (col.padding) wrapWidth -= (col.padding[left] || 0) + (col.padding[right] || 0)
 return wrapWidth
}

UI.prototype._columnWidths = function (row) {
 var _this = this,
 widths = [],
 unset = row.length,
 unsetWidth,
 remainingWidth = this.width

 // column widths can be set in config.
 row.forEach(function (col, i) {
 if (col.width) {
 unset--
 widths[i] = col.width
 remainingWidth -= col.width
 } else {
 widths[i] = undefined
 }
 })

 // any unset widths should be calculated.
 if (unset) unsetWidth = Math.floor(remainingWidth / unset)
 widths.forEach(function (w, i) {
 if (!_this.wrap) widths[i] = row[i].width || row[i].text.length
 else if (w === undefined) widths[i] = Math.max(unsetWidth, _minWidth(row[i]))
 })

 return widths
}

// calculates the minimum width of
// a column, based on padding preferences.
function _minWidth (col) {
 var padding = col.padding || []

 return 1 + (padding[left] || 0) + (padding[right] || 0)
}

module.exports = function (opts) {
 opts = opts || {}

 return new UI({
 width: (opts || {}).width || 80,
 wrap: typeof opts.wrap === 'boolean' ? opts.wrap : true
 })
}