asteris-llc/converge

// Copyright © 2016 Asteris, LLC
//
// 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 tmpltools

import (
    "bytes"
    "fmt"
    "strings"
    "text/template"

    "github.com/asteris-llc/converge/resource"
)

// ExtendedTemplate provides information about extended template rendering
type ExtendedTemplate struct {
    Color bool
}

// New generates a new template.Template with the functions from the extended template
func (tmpl *ExtendedTemplate) New(source string) (*template.Template, error) {
    reset := "\x1b[0m"
    funcs := map[string]interface{}{
        // colors
        "black":   tmpl.styled(func(in string) string { return "\x1b[30m" + in + reset }),
        "red":     tmpl.styled(func(in string) string { return "\x1b[31m" + in + reset }),
        "green":   tmpl.styled(func(in string) string { return "\x1b[32m" + in + reset }),
        "yellow":  tmpl.styled(func(in string) string { return "\x1b[33m" + in + reset }),
        "blue":    tmpl.styled(func(in string) string { return "\x1b[34m" + in + reset }),
        "magenta": tmpl.styled(func(in string) string { return "\x1b[35m" + in + reset }),
        "cyan":    tmpl.styled(func(in string) string { return "\x1b[36m" + in + reset }),
        "white":   tmpl.styled(func(in string) string { return "\x1b[37m" + in + reset }),

        // utils
        "indent":      tmpl.indent,
        "diff":        tmpl.diff,
        "showWarning": showWarning,
    }
    return template.New("").Funcs(funcs).Parse(source)
}

func (tmpl *ExtendedTemplate) styled(style func(string) string) func(string) string {
    if !tmpl.Color {
        return func(in string) string { return in }
    }

    return style
}

func (tmpl *ExtendedTemplate) diff(before, after string) (string, error) {
    // remember when modifying these that diff is responsible for leading
    // whitespace
    if !strings.Contains(strings.TrimSpace(before), "\n") && !strings.Contains(strings.TrimSpace(after), "\n") {
        return fmt.Sprintf(" %q => %q", strings.TrimSpace(before), strings.TrimSpace(after)), nil
    }

    newTmpl, err := tmpl.New(`before:
{{indent .Before}}
after:
{{indent .After}}`)
    if err != nil {
        return "", err
    }

    buf := new(bytes.Buffer)
    err = newTmpl.Execute(buf, struct{ Before, After string }{before, after})

    return "\n" + tmpl.indent(tmpl.indent(buf.String())), err
}

func (tmpl *ExtendedTemplate) indent(in string) string {
    return "\t" + strings.Replace(in, "\n", "\n\t", -1)
}

func (tmpl *ExtendedTemplate) empty(s string) bool {
    return s == ""
}

func showWarning(c resource.HealthStatusCode) string {
    switch c {
    case resource.StatusHealthy:
        return "Healthy"
    case resource.StatusWarning:
        return "Warning"
    case resource.StatusError:
        return "Error"
    default:
        return "Fatal: Unkown Error"
    }
}

// Run creates a template extension with the provided color setting and then
// runs it with the provided template source
func Run(color bool, source string) (*template.Template, error) {
    return (&ExtendedTemplate{Color: color}).New(source)
}