// Copyright 2019 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package axes

// value.go contains code dealing with values on the line chart.

import (
	"fmt"
	"math"

	"github.com/mum4k/termdash/internal/numbers"
)

// Value represents one value.
type Value struct {
	// Value is the original unmodified value.
	Value float64
	// Rounded is the value rounded up to the nonZeroPlaces number of non-zero
	// decimal places.
	Rounded float64
	// ZeroDecimals indicates how many decimal places in Rounded have a value
	// of zero.
	ZeroDecimals int
	// NonZeroDecimals indicates the rounding precision used, it is provided on
	// a call to newValue.
	NonZeroDecimals int

	// text value if this value was constructed using NewTextValue.
	text string
}

// String implements fmt.Stringer.
func (v *Value) String() string {
	return fmt.Sprintf("Value{Round(%v) => %v}", v.Value, v.Rounded)
}

// NewValue returns a new instance representing the provided value, rounding
// the value up to the specified number of non-zero decimal places.
func NewValue(v float64, nonZeroDecimals int) *Value {
	r, zd := numbers.RoundToNonZeroPlaces(v, nonZeroDecimals)
	return &Value{
		Value:           v,
		Rounded:         r,
		ZeroDecimals:    zd,
		NonZeroDecimals: nonZeroDecimals,
	}
}

// NewTextValue constructs a value out of the provided text.
func NewTextValue(text string) *Value {
	return &Value{
		Value:   math.NaN(),
		Rounded: math.NaN(),
		text:    text,
	}
}

// Text returns textual representation of the value.
func (v *Value) Text() string {
	if v.text != "" {
		return v.text
	}
	if math.Ceil(v.Rounded) == v.Rounded {
		return fmt.Sprintf("%.0f", v.Rounded)
	}

	format := fmt.Sprintf("%%.%df", v.NonZeroDecimals+v.ZeroDecimals)
	t := fmt.Sprintf(format, v.Rounded)
	if len(t) > 10 {
		t = fmt.Sprintf("%.2e", v.Rounded)
	}
	return t
}