package log

import (
	"gitee.com/sy_183/go-common/errors"
)

type hooked struct {
	Core
	funcs []func(Entry) error
}

// RegisterHooks wraps a Core and runs a collection of user-defined callback
// hooks each time a message is logged. Execution of the callbacks is blocking.
//
// This offers users an easy way to register simple callbacks (e.g., metrics
// collection) without implementing the full Core interface.
func RegisterHooks(core Core, hooks ...func(Entry) error) Core {
	funcs := append([]func(Entry) error{}, hooks...)
	return &hooked{
		Core:  core,
		funcs: funcs,
	}
}

func (h *hooked) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
	// Let the wrapped Core decide whether to log this message or not. This
	// also gives the downstream a chance to register itself directly with the
	// CheckedEntry.
	if downstream := h.Core.Check(ent, ce); downstream != nil {
		return downstream.AddCore(ent, h)
	}
	return ce
}

func (h *hooked) With(fields []Field) Core {
	return &hooked{
		Core:  h.Core.With(fields),
		funcs: h.funcs,
	}
}

func (h *hooked) Write(ent Entry, _ []Field) error {
	// Since our downstream had a chance to register itself directly with the
	// CheckedMessage, we don't need to call it here.
	var err error
	for i := range h.funcs {
		err = errors.Append(err, h.funcs[i](ent))
	}
	return err
}