efritz/derision

package template

import (
    "encoding/json"
    "fmt"
    tmpl "text/template"
)

type jsonTemplate struct {
    StatusCode string              `json:"status_code"`
    Headers    map[string][]string `json:"headers"`
    Body       string              `json:"body"`
}

func Unmarshal(payload []byte) (Template, error) {
    t := &jsonTemplate{}
    if err := json.Unmarshal(payload, &t); err != nil {
        return nil, fmt.Errorf("failed to unmarshal payload (%s)", err.Error())
    }

    statusCode, err := compile(t.StatusCode)
    if err != nil {
        return nil, fmt.Errorf("illegal status code template")
    }

    headers := map[string][]*tmpl.Template{}
    for name, values := range t.Headers {
        templates := []*tmpl.Template{}
        for _, value := range values {
            template, err := compile(value)
            if err != nil {
                return nil, fmt.Errorf("illegal header template")
            }

            templates = append(templates, template)
        }

        headers[name] = templates
    }

    body, err := compile(t.Body)
    if err != nil {
        return nil, fmt.Errorf("illegal body template")
    }

    return &template{
        statusCode: statusCode,
        headers:    headers,
        body:       body,
    }, nil
}

func compile(template string) (*tmpl.Template, error) {
    return tmpl.New("").Parse(template)
}