module.go

// Copyright (c) 2022 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package fx

import (
	"fmt"

	"go.uber.org/dig"
	"go.uber.org/fx/fxevent"
	"go.uber.org/fx/internal/fxreflect"
	"go.uber.org/multierr"
)

// A container represents a set of constructors to provide
// dependencies, and a set of functions to invoke once all the
// dependencies have been initialized.
//
// This definition corresponds to the dig.Container and dig.Scope.
type container interface {
	Invoke(interface{}, ...dig.InvokeOption) error
	Provide(interface{}, ...dig.ProvideOption) error
	Decorate(interface{}, ...dig.DecorateOption) error
}

// Module is a named group of zero or more fx.Options.
// A Module creates a scope in which certain operations are taken
// place. For more information, see [Decorate], [Replace], or [Invoke].
func Module(name string, opts ...Option) Option {
	mo := moduleOption{
		name:    name,
		options: opts,
	}
	return mo
}

type moduleOption struct {
	name    string
	options []Option
}

func (o moduleOption) String() string {
	return fmt.Sprintf("fx.Module(%q, %v)", o.name, o.options)
}

func (o moduleOption) apply(mod *module) {
	// This get called on any submodules' that are declared
	// as part of another module.

	// 1. Create a new module with the parent being the specified
	// module.
	// 2. Apply child Options on the new module.
	// 3. Append it to the parent module.
	newModule := &module{
		name:   o.name,
		parent: mod,
		app:    mod.app,
	}
	for _, opt := range o.options {
		opt.apply(newModule)
	}
	mod.modules = append(mod.modules, newModule)
}

type module struct {
	parent         *module
	name           string
	scope          scope
	provides       []provide
	invokes        []invoke
	decorators     []decorator
	modules        []*module
	app            *App
	log            fxevent.Logger
	fallbackLogger fxevent.Logger
	logConstructor *provide
}

// scope is a private wrapper interface for dig.Container and dig.Scope.
// We can consider moving this into Fx using type constraints after Go 1.20
// is released and 1.17 is deprecated.
type scope interface {
	Decorate(f interface{}, opts ...dig.DecorateOption) error
	Invoke(f interface{}, opts ...dig.InvokeOption) error
	Provide(f interface{}, opts ...dig.ProvideOption) error
	Scope(name string, opts ...dig.ScopeOption) *dig.Scope
	String() string
}

// builds the Scopes using the App's Container. Note that this happens
// after applyModules' are called because the App's Container needs to
// be built for any Scopes to be initialized, and applys' should be called
// before the Container can get initialized.
func (m *module) build(app *App, root *dig.Container) {
	if m.parent == nil {
		m.scope = root
	} else {
		parentScope := m.parent.scope
		m.scope = parentScope.Scope(m.name)
		// use parent module's logger by default
		m.log = m.parent.log
	}

	if m.logConstructor != nil {
		// Since user supplied a custom logger, use a buffered logger
		// to hold all messages until user supplied logger is
		// instantiated. Then we flush those messages after fully
		// constructing the custom logger.
		m.fallbackLogger, m.log = m.log, new(logBuffer)
	}

	for _, mod := range m.modules {
		mod.build(app, root)
	}
}

func (m *module) provideAll() {
	for _, p := range m.provides {
		m.provide(p)
	}

	for _, m := range m.modules {
		m.provideAll()
	}
}

func (m *module) provide(p provide) {
	if m.app.err != nil {
		return
	}

	var info dig.ProvideInfo
	if err := runProvide(m.scope, p, dig.FillProvideInfo(&info), dig.Export(true)); err != nil {
		m.app.err = err
	}
	var ev fxevent.Event
	switch {
	case p.IsSupply:
		ev = &fxevent.Supplied{
			TypeName:   p.SupplyType.String(),
			ModuleName: m.name,
			Err:        m.app.err,
		}

	default:
		outputNames := make([]string, len(info.Outputs))
		for i, o := range info.Outputs {
			outputNames[i] = o.String()
		}

		ev = &fxevent.Provided{
			ConstructorName: fxreflect.FuncName(p.Target),
			ModuleName:      m.name,
			OutputTypeNames: outputNames,
			Err:             m.app.err,
		}
	}
	m.log.LogEvent(ev)
}

// Constructs custom loggers for all modules in the tree
func (m *module) constructAllCustomLoggers() {
	if m.logConstructor != nil {
		if buffer, ok := m.log.(*logBuffer); ok {
			// default to parent's logger if custom logger constructor fails
			if err := m.constructCustomLogger(buffer); err != nil {
				m.app.err = multierr.Append(m.app.err, err)
				m.log = m.fallbackLogger
				buffer.Connect(m.log)
			}
		}
		m.fallbackLogger = nil
	} else if m.parent != nil {
		m.log = m.parent.log
	}

	for _, mod := range m.modules {
		mod.constructAllCustomLoggers()
	}
}

// Mirroring the behavior of app.constructCustomLogger
func (m *module) constructCustomLogger(buffer *logBuffer) (err error) {
	p := m.logConstructor
	fname := fxreflect.FuncName(p.Target)
	defer func() {
		m.log.LogEvent(&fxevent.LoggerInitialized{
			Err:             err,
			ConstructorName: fname,
		})
	}()

	// TODO: Use dig.FillProvideInfo to inspect the provided constructor
	// and fail the application if its signature didn't match.
	if err := m.scope.Provide(p.Target); err != nil {
		return fmt.Errorf("fx.WithLogger(%v) from:\n%+v\nin Module: %q\nFailed: %w",
			fname, p.Stack, m.name, err)
	}

	return m.scope.Invoke(func(log fxevent.Logger) {
		m.log = log
		buffer.Connect(log)
	})
}

func (m *module) executeInvokes() error {
	for _, m := range m.modules {
		if err := m.executeInvokes(); err != nil {
			return err
		}
	}

	for _, invoke := range m.invokes {
		if err := m.executeInvoke(invoke); err != nil {
			return err
		}
	}

	return nil
}

func (m *module) executeInvoke(i invoke) (err error) {
	fnName := fxreflect.FuncName(i.Target)
	m.log.LogEvent(&fxevent.Invoking{
		FunctionName: fnName,
		ModuleName:   m.name,
	})
	err = runInvoke(m.scope, i)
	m.log.LogEvent(&fxevent.Invoked{
		FunctionName: fnName,
		ModuleName:   m.name,
		Err:          err,
		Trace:        fmt.Sprintf("%+v", i.Stack), // format stack trace as multi-line
	})
	return err
}

func (m *module) decorate() (err error) {
	for _, decorator := range m.decorators {
		var info dig.DecorateInfo
		err := runDecorator(m.scope, decorator, dig.FillDecorateInfo(&info))
		outputNames := make([]string, len(info.Outputs))
		for i, o := range info.Outputs {
			outputNames[i] = o.String()
		}

		if decorator.IsReplace {
			m.log.LogEvent(&fxevent.Replaced{
				ModuleName:      m.name,
				OutputTypeNames: outputNames,
				Err:             err,
			})
		} else {

			m.log.LogEvent(&fxevent.Decorated{
				DecoratorName:   fxreflect.FuncName(decorator.Target),
				ModuleName:      m.name,
				OutputTypeNames: outputNames,
				Err:             err,
			})
		}
		if err != nil {
			return err
		}
	}
	for _, m := range m.modules {
		if err := m.decorate(); err != nil {
			return err
		}
	}
	return nil
}