/
jsonnet.go
261 lines (218 loc) · 6.3 KB
/
jsonnet.go
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package jsonnet
import (
"encoding/json"
"fmt"
"log/slog"
"regexp"
"strings"
"time"
"github.com/fatih/color"
_jsonnet "github.com/google/go-jsonnet"
"github.com/google/go-jsonnet/ast"
"github.com/teris-io/shortid"
"github.com/tidwall/gjson"
)
var HeaderMarker = "\n###\n"
type JsonnetEngine struct {
vm *_jsonnet.VM
template string
Options EngineOptions
}
type EngineOptions struct {
Debug bool
DryRun bool
UseColor bool
LibraryPaths []string
Meta any
}
type TemplateOption func(*EngineOptions) *EngineOptions
func WithDebug(v bool) TemplateOption {
return func(opt *EngineOptions) *EngineOptions {
opt.Debug = v
return opt
}
}
func WithDryRun(v bool) TemplateOption {
return func(opt *EngineOptions) *EngineOptions {
opt.DryRun = v
return opt
}
}
func WithColorStackTrace(v bool) TemplateOption {
return func(opt *EngineOptions) *EngineOptions {
opt.UseColor = v
return opt
}
}
func WithMetaData(v any) TemplateOption {
return func(opt *EngineOptions) *EngineOptions {
opt.Meta = v
return opt
}
}
func WithLibraryPaths(paths ...string) TemplateOption {
return func(opt *EngineOptions) *EngineOptions {
opt.LibraryPaths = paths
return opt
}
}
type vmConfig struct {
evalJpath []string
}
func makeVMConfig() vmConfig {
return vmConfig{
evalJpath: []string{},
}
}
func NewJsonnetVM(useColor bool, paths ...string) *_jsonnet.VM {
vm := _jsonnet.MakeVM()
if useColor {
vm.ErrorFormatter.SetColorFormatter(color.New(color.FgRed).Fprintf)
}
vmConfig := makeVMConfig()
for i := len(paths) - 1; i >= 0; i-- {
slog.Info("Adding jsonnet path.", "path", paths[i])
vmConfig.evalJpath = append(vmConfig.evalJpath, paths[i])
}
vm.Importer(&_jsonnet.FileImporter{
JPaths: vmConfig.evalJpath,
})
return vm
}
func NewEngine(tmpl string, opts ...TemplateOption) *JsonnetEngine {
engine := &JsonnetEngine{}
config := &EngineOptions{}
for _, opt := range opts {
opt(config)
}
engine.vm = NewJsonnetVM(config.UseColor, config.LibraryPaths...)
sb := strings.Builder{}
metaD, err := json.Marshal(config.Meta)
if err == nil {
if strings.HasPrefix(string(metaD), "{") && strings.HasSuffix(string(metaD), "}") {
sb.WriteString(fmt.Sprintf("local meta = %s;\n", metaD))
} else if strings.HasPrefix(string(metaD), "{") && strings.HasPrefix(string(metaD), "}") {
sb.WriteString(fmt.Sprintf("local meta = %s;\n", metaD))
} else {
sb.WriteString(fmt.Sprintf("local meta = '%s';\n", metaD))
}
} else {
sb.WriteString("local meta = {};\n")
}
sb.WriteString("local _ = {Now: function() std.native('Now')(), Get: function(o, key, defaultValue=null) std.native('Get')(o, key, defaultValue), ReplacePattern: function(s, from, to='') std.native('ReplacePattern')(s, from, to),ID: function() std.native('ID')(),};\n")
sb.WriteString(removeHeader(tmpl))
engine.template = sb.String()
engine.Options = *config
engine.addFunctions()
return engine
}
func getStringParameter(parameters []interface{}, i int) string {
if len(parameters) > 0 && i < len(parameters) {
return fmt.Sprintf("%v", parameters[i])
}
return ""
}
func getParameter(parameters []interface{}, i int) any {
if len(parameters) > 0 && i < len(parameters) {
return parameters[i]
}
return nil
}
func (e *JsonnetEngine) Debug() bool {
return e.Options.Debug
}
func (e *JsonnetEngine) DryRun() bool {
return e.Options.DryRun
}
func (e *JsonnetEngine) addFunctions() {
e.vm.NativeFunction(&_jsonnet.NativeFunction{
Name: "Now",
Func: func(parameters []interface{}) (interface{}, error) {
return time.Now().Format(time.RFC3339Nano), nil
},
})
e.vm.NativeFunction(&_jsonnet.NativeFunction{
Name: "NowNano",
Func: func(parameters []interface{}) (interface{}, error) {
return time.Now().Format(time.RFC3339Nano), nil
},
})
e.vm.NativeFunction(&_jsonnet.NativeFunction{
Name: "ReplacePattern",
Params: ast.Identifiers{"value", "from", "to"},
Func: func(parameters []interface{}) (interface{}, error) {
value := getStringParameter(parameters, 0)
from := getStringParameter(parameters, 1)
to := getStringParameter(parameters, 2)
pattern, err := regexp.Compile(from)
if err != nil {
return "", err
}
return pattern.ReplaceAllString(value, to), nil
},
})
e.vm.NativeFunction(&_jsonnet.NativeFunction{
Name: "ID",
Func: func(parameters []interface{}) (interface{}, error) {
v, err := shortid.Generate()
if err != nil {
return "", err
}
return v, nil
},
})
e.vm.NativeFunction(&_jsonnet.NativeFunction{
Name: "Get",
Params: ast.Identifiers{"obj", "prop", "default"},
Func: func(parameters []interface{}) (interface{}, error) {
obj := getParameter(parameters, 0)
key := getStringParameter(parameters, 1)
defaultValue := getParameter(parameters, 2)
// TODO: Try to avoid converting from map to json again
objB, err := json.Marshal(obj)
if err != nil {
return defaultValue, nil
}
if v := gjson.GetBytes(objB, key); v.Exists() {
return v.Value(), nil
}
return defaultValue, nil
},
})
}
// Remove the header as this is just used to locally test the template
func removeHeader(tmpl string) string {
if i := strings.Index(tmpl, HeaderMarker); i != -1 {
return tmpl[i:]
}
return tmpl
}
func (e *JsonnetEngine) Execute(topic, input string, variables string) (string, error) {
e.vm.ExtVar("message", "do something")
sb := strings.Builder{}
sb.WriteString(fmt.Sprintf("local topic = '%s';\n", topic))
inputIsObject := json.Valid([]byte(input))
if inputIsObject {
sb.WriteString(fmt.Sprintf("local _input = %s;\n", input))
} else {
sb.WriteString(fmt.Sprintf("local _input = '%s';\n", input))
}
slog.Info("json template.", "variables", variables)
if variables == "" {
variables = "{}"
}
sb.WriteString(fmt.Sprintf("local variables = %s;\n", variables))
sb.WriteString("local message = if std.isObject(_input) then _input + {_ctx:: null} else _input;\n")
if inputIsObject {
sb.WriteString("local ctx = {lvl:0} + if std.isObject(_input) then std.get(_input, '_ctx', {}) else {};\n")
} else {
sb.WriteString("local ctx = {lvl:0};\n")
}
sb.WriteString(e.template)
sb.WriteString(" + {message+: {_ctx+: ctx + {lvl: std.get(ctx, 'lvl', 0) + 1}}}")
output, err := e.vm.EvaluateAnonymousSnippet("file", sb.String())
if e.Debug() {
fmt.Printf("Template: \n\n%s\n\n", sb.String())
}
return output, err
}