// Package output defines the pluggable destination interface and its
// implementations (currently Discord webhook).
package output

import (
	"context"
	"fmt"

	"github.com/ytshih/stonks/internal/config"
	"github.com/ytshih/stonks/internal/report"
)

// Output delivers the final report somewhere (Discord, Slack, email, ...).
// Implementations decide how to render report.Text and the optional
// report.Recommendations (e.g. Discord sends the text as chunked messages
// followed by a short recommendations embed).
type Output interface {
	Name() string
	Send(ctx context.Context, rep report.Report) error
}

// Constructor builds an Output from its PluginConfig (name + params).
type Constructor func(cfg config.PluginConfig) (Output, error)

var registry = map[string]Constructor{}

// Register makes an output constructor available under name. Called from
// each output implementation's init().
func Register(name string, ctor Constructor) {
	if _, exists := registry[name]; exists {
		panic(fmt.Sprintf("output: constructor already registered for %q", name))
	}
	registry[name] = ctor
}

// Build looks up the constructor for cfg.Name and invokes it.
func Build(cfg config.PluginConfig) (Output, error) {
	ctor, ok := registry[cfg.Name]
	if !ok {
		return nil, fmt.Errorf("output: no output registered for %q", cfg.Name)
	}
	return ctor(cfg)
}