inventory.go

package skipper

import (
	"fmt"
	"path/filepath"
	"strings"

	"github.com/spf13/afero"
)

// Inventory is the collection of classes and targets.
// The inventory wraps everything together and is capable of producing a single, coherent [Data]
// which can then be used inside the templates.
type Inventory struct {
	fs          afero.Fs
	classPath   string
	targetPath  string
	secretPath  string
	secretFiles []*SecretFile
	classFiles  []*Class
	targetFiles []*Target
}

// NewInventory creates a new Inventory with the given afero.Fs.
// At least one extension must be provided, otherwise an error is returned.
func NewInventory(fs afero.Fs, classPath, targetPath, secretPath string) (*Inventory, error) {
	if fs == nil {
		return nil, fmt.Errorf("fs cannot be nil")
	}
	if classPath == "" {
		return nil, fmt.Errorf("classPath cannot be empty")
	}
	if targetPath == "" {
		return nil, fmt.Errorf("targetPath cannot be empty")
	}
	if secretPath == "" {
		return nil, fmt.Errorf("secretPath cannot be empty")
	}

	if strings.EqualFold(classPath, targetPath) {
		return nil, fmt.Errorf("classPath cannot be the same as targetPath")
	}
	if strings.EqualFold(classPath, secretPath) {
		return nil, fmt.Errorf("classPath cannot be the same as secretPath")
	}
	if strings.EqualFold(targetPath, secretPath) {
		return nil, fmt.Errorf("targetPath cannot be the same as secretPath")
	}

	inv := &Inventory{
		fs:         fs,
		classPath:  classPath,
		targetPath: targetPath,
		secretPath: secretPath,
	}

	err := inv.load()
	if err != nil {
		return nil, err
	}

	return inv, nil
}

// load will discover and load all classes and targets given the paths.
// It will also ensure that all targets only use classes which are actually defined.
func (inv *Inventory) load() error {
	err := YamlFileLoader(inv.fs, inv.classPath, classYamlFileLoader(&inv.classFiles))
	if err != nil {
		return fmt.Errorf("unable to load class files: %w", err)
	}
	err = YamlFileLoader(inv.fs, inv.targetPath, targetYamlFileLoader(&inv.targetFiles))
	if err != nil {
		return fmt.Errorf("unable to load target files: %w", err)
	}
	err = YamlFileLoader(inv.fs, inv.secretPath, secretYamlFileLoader(&inv.secretFiles))
	if err != nil {
		return fmt.Errorf("unable to load secret files: %w", err)
	}

	// check for all targets whether they use classes which actually exist
	for _, target := range inv.targetFiles {
		// check the used wildcard classes by the target
		// and add them to the "UsedClasses" field if they exist
		for _, use := range target.UsedWildcardClasses {
			for _, class := range inv.classFiles {
				usePrefix := strings.TrimRight(use, "*")

				if strings.HasPrefix(class.Name, usePrefix) {
					target.SkipperConfig.Classes = append(target.SkipperConfig.Classes, class.Name)
				}

			}
		}
	}

	return nil
}

// GetSkipperConfig merges SkipperConfig of the target and it's used classes into one effective configuration.
func (inv *Inventory) GetSkipperConfig(targetName string) (config *SkipperConfig, err error) {
	var configurations []*SkipperConfig

	// load SkipperConfig of target
	target := inv.GetTarget(targetName)
	if target == nil {
		return nil, fmt.Errorf("target could not be loaded: %s", targetName)
	}
	configurations = append(configurations, target.SkipperConfig)

	// load all GetSkipperConfigs from used classes
	for _, className := range target.SkipperConfig.Classes {
		class := inv.GetClass(className)
		if class == nil {
			return nil, fmt.Errorf("target '%s' uses class which does not exist: %s", targetName, className)
		}
		configurations = append(configurations, class.Configuration)
	}

	return MergeSkipperConfig(configurations...), nil
}

// GetUsedClasses returns the loaded classes which are used by the given target.
func (inv *Inventory) GetUsedClasses(targetName string) ([]*Class, error) {
	target := inv.GetTarget(targetName)
	if target == nil {
		return nil, fmt.Errorf("target could not be loaded: %s", targetName)
	}

	var classes []*Class
	for _, className := range target.SkipperConfig.Classes {
		class := inv.GetClass(className)
		if class == nil {
			return nil, fmt.Errorf("target '%s' uses class which does not exist: %s", targetName, className)
		}
		classes = append(classes, class)
	}

	return classes, nil
}

// Data loads the required inventory data map given the target.
// This is where variables and secrets are handled and eventually replaced.
// The resulting Data is what can be passed to the templates.
func (inv *Inventory) Data(targetName string, predefinedVariables map[string]interface{}, revealSecrets bool) (data Data, err error) {
	data = make(Data)

	target := inv.GetTarget(targetName)
	if target == nil {
		return nil, fmt.Errorf("target could not be loaded: %s", targetName)
	}

	// load all classes as defined by the target
	classes, err := inv.GetUsedClasses(targetName)
	if err != nil {
		return nil, err
	}

	// merge data from all classes into Data, preserving the class path.
	// A class with path "foo.bar.class" will be added like: Data["foo"]["bar"]["baz"] = classData
	{
		// ensure that the loaded class-data does not conflict
		// If two classes with the same root-key are selected, we cannot continue.
		// We could attempt to perform a 'smart' merge or apply some precendende rules, but
		// this will inevitably cause unexpected behaviour which is not what we want.
		for _, class := range classes {

			// If the class name has multiple segments (foo.bar.baz), we will need to
			// add the keys do Data, so that Data[foo][bar][baz] is where the data of the class will be added.
			classSegments := strings.Split(class.Name, ".")
			if len(classSegments) > 1 {
				tmp := data

				for _, segment := range classSegments {

					if !tmp.HasKey(segment) {
						tmp[segment] = make(Data)
					}

					// as long as the current segment is not the RootKey, shift tmp by the segment
					if segment != class.RootKey() {
						tmp = tmp[segment].(Data)
						continue
					}

					// add class data to RootKey. Since we're here, RootKey==segment, hence we can add it here.
					if class.Data().Get(class.RootKey()) == nil {
						continue
					}
					tmp[class.RootKey()] = class.Data().Get(class.RootKey())

				}
			} else {
				// class does not have a dot separator, hence we just check if the RootKey exists and add the data
				if _, exists := data[class.RootKey()]; exists {
					return nil, fmt.Errorf("duplicate key '%s' registered by class '%s'", class.RootKey(), class.Name)
				}
				data[class.RootKey()] = class.Data().Get(class.RootKey())
			}

		}
	}

	// Merge target into Data, overwriting any existing values which were defined in classes because target data has precedence over class data.
	// Any key which is not added to the main Data (because the keys did not already exist), will be added.
	targetData := target.Data()
	data = data.MergeReplace(targetData)

	// add Skipper pre-defined variables
	if predefinedVariables == nil {
		predefinedVariables = make(map[string]interface{})
	}
	predefinedVariables["target_name"] = targetName

	// replace all ordinary variables (`${...}`) inside the data
	err = ReplaceVariables(data, inv.classFiles, predefinedVariables)
	if err != nil {
		return nil, err
	}

	// call managment
	{
		calls, err := FindCalls(data)
		if err != nil {
			return nil, err
		}

		for _, call := range calls {
			// replace call with function result
			// sourceValue is the value where the variable is. It needs to be replaced with an actual value
			sourceValue, err := data.GetPath(call.Identifier...)
			if err != nil {
				return nil, err
			}

			// Replace the full variable name (${variable}) with the targetValue
			sourceValue = strings.ReplaceAll(fmt.Sprint(sourceValue), call.FullName(), call.Execute())
			data.SetPath(sourceValue, call.Identifier...)
		}
	}

	// we need to reload the target configuration as it will derive it's configuration from the Data
	// of a previous state. Since the calls can modify the target configuration as well, we have to reload it.
	target.ReloadConfiguration()

	// secret management
	// initialize drivers, load or create secrets and eventually replace them if `revealSecrets` is true.
	{
		// fetch and configure secret drivers configured by the target
		for driverName, driverConfig := range target.Configuration.Secrets.Drivers {
			driver, err := SecretDriverFactory(driverName)
			if err != nil {
				return nil, fmt.Errorf("target contains invalid secret driver configuration: %w", err)
			}

			if drv, ok := driver.(ConfigurableSecretDriver); ok {
				if config, ok := driverConfig.(map[string]interface{}); ok {
					err = drv.Configure(config)
					if err != nil {
						return nil, fmt.Errorf("failed to configure driver '%s': %w", driverName, err)
					}
				} else {
					return nil, fmt.Errorf("driver configuration for '%s' is not map[string]interface{}", driverName)
				}
			}
		}

		// find all secrets or attempt to create them if an alternative action is set
		secrets, err := FindOrCreateSecrets(data, inv.secretFiles, inv.secretPath, inv.fs)
		if err != nil {
			return nil, err
		}

		// attempt load all secret files and replace the variables with the actual values if revealSecrets is true
		for _, secret := range secrets {
			if !secret.Exists(inv.fs) {
				return nil, fmt.Errorf("undefined secret '%s': file does not exist: %s", secret.FullName(), secret.SecretFile.Path)
			}

			err = secret.Load(inv.fs)
			if err != nil {
				return nil, fmt.Errorf("failed to load secret: %w", err)
			}

			// if the flag is true, all secret variables will be replaced by their actual value.
			// CAUTION: This is not something you want to do during local development, only inside your CI pipeline when the compiled output is ephemeral.
			if revealSecrets {
				err = ReplaceSecret(data, secret)
				if err != nil {
					return nil, fmt.Errorf("failed to replace secret value: %w", err)
				}
			}
		}
	}

	return data, nil
}

// AddExternalClass can be used to dynamically create class files.
// The given data will be written into `classFilePath`, overwriting any existing file.
//
// The class path is first normalized to match the existing `Inventory.classPath`.
//
// After that, the root-key of the data is adjusted to match the fileName which is extracted from `classFilePath`.
// This has to be done in order to comply Skipper rules where the class-filename must also be the root-key of any given class.
//
// A new file inside the Skipper class path is created which makes it available for loading.
// In order to prevent confusion, a file header is added to indicate that the class was generated.
func (inv *Inventory) AddExternalClass(data map[string]any, classFilePath string) error {
	if data == nil {
		return fmt.Errorf("cannot add external class without data")
	}
	if classFilePath == "" {
		return fmt.Errorf("classFilePath cannot be empty")
	}

	// normalize classFilePath
	classFilePath = strings.TrimLeft(classFilePath, "./")
	if !strings.HasPrefix(classFilePath, inv.classPath) {
		classFilePath = filepath.Join(inv.classPath, classFilePath)
	}

	// adjust the root key to match the filename because this is what Skipper expects
	fileName := filepath.Base(classFilePath)
	rootKey := strings.TrimSuffix(fileName, filepath.Ext(fileName))

	// create new data and set the root key
	classData := make(Data)
	classData[rootKey] = data

	// warn the user that this class is generated and should not be edited manually
	classBytes := []byte("---\n# This is a dynamically generated class file. DO NOT EDIT!\n")
	classBytes = append(classBytes, classData.Bytes()...)

	// write the class into the inventory filesystem
	classFile, err := CreateNewYamlFile(inv.fs, classFilePath, classBytes)
	if err != nil {
		return err
	}

	newClass, err := NewClass(classFile, classFilePath)
	if err != nil {
		return err
	}

	inv.classFiles = append(inv.classFiles, newClass)

	return nil
}

// GetTarget attempts to return a target struct given a target name.
// If the target could not be found, nil is returned.
func (inv *Inventory) GetTarget(name string) *Target {
	for _, target := range inv.targetFiles {
		if strings.ToLower(name) == strings.ToLower(target.Name) {
			return target
		}
	}
	return nil
}

// GetClass attempts to return a Class, given a name.
// If the class does not exist, nil is returned.
func (inv *Inventory) GetClass(name string) *Class {
	for _, class := range inv.classFiles {
		if class.Name == name {
			return class
		}
	}
	return nil
}

// GetAllTargets returns all discovered Targets
func (inv *Inventory) GetAllTargets() []*Target {
	return inv.targetFiles
}

// GetAllClasses returns all discovered Classes
func (inv *Inventory) GetAllClasses() []*Class {
	return inv.classFiles
}