// Copyright (C) 2022 Mya Pitzeruse
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
//

package okit

import (
	"context"
)

// Logger defines common operations for writing log messages.
type Logger interface {
	// Debug adds a debug message to the event stream, if configured.
	Debug(msg string, tags ...Tag)
	// Info adds an informational message to the event stream.
	Info(msg string, tags ...Tag)
	// Warn adds a warning to the event stream.
	Warn(msg string, tags ...Tag)
	// Error adds an error to the event stream.
	Error(msg string, tags ...Tag)
}

// Emitter is used to send multidimensional events to the underlying stream.
type Emitter interface {
	// Emit sends the named event along the underlying stream.
	Emit(event string, tags ...Tag)
}

// Observer allows metrics to be captured and emit from the system.
type Observer interface {
	// Observe records the associated metric and value.
	Observe(metric string, value float64, tags ...Tag)
}

// DoneFunc represents a function that is called when a trace is complete.
type DoneFunc func()

// Tracer allows method calls to be instrumented for debugging.
type Tracer interface {
	// Trace captures the method calling context and returns a function that can be invoked to complete the trace.
	Trace(ctx context.Context, tags ...Tag) (context.Context, DoneFunc)
}

// Span defines an internal structure for tracking traces across an application. This structure is only used for
// tracking purposes and direct modifications will not be reflected.
type Span struct {
	// TraceID specifies an identifier for the overall trace event. This value is often inherited from a parent.
	TraceID string
	// ID uniquely identifies a span within a trace.
	ID string
	// ParentID points to the id of the wrapping span.
	ParentID string
}

type Wither[T any] interface {
	With(tags ...Tag) T
}

// Interface defines an abstraction that contains all the user-facing functions.
type Interface[T any] interface {
	Logger
	Emitter
	Observer
	Tracer
	Wither[T]
}