// Package usecase holds Tapir's application core: the engine that detects new
// videos, resolves transcripts, summarizes, and delivers to sinks. It depends
// only on internal/ports and internal/domain.
//
// This is a SCAFFOLD. Methods return ErrNotImplemented so the acceptance tests
// in test/acceptance fail RED. Implementing them to make those tests pass is
// the first build task (see the build issue). Behaviour is specified in
// docs/use-cases/*.feature.
package usecase

import (
	"context"
	"errors"

	"gitea.d-ma.be/mathias/tapir/internal/domain"
	"gitea.d-ma.be/mathias/tapir/internal/ports"
)

// ErrNotImplemented marks scaffold methods awaiting implementation.
var ErrNotImplemented = errors.New("not implemented")

// Engine is the provider- and sink-agnostic core.
type Engine struct {
	Source ports.VideoSource
	AI     ports.Summarizer
	Sinks  []ports.Sink
}

// NewEngine wires the engine from its ports.
func NewEngine(src ports.VideoSource, ai ports.Summarizer, sinks ...ports.Sink) *Engine {
	return &Engine{Source: src, AI: ai, Sinks: sinks}
}

// ProcessResult reports what happened for one video.
type ProcessResult struct {
	Video   domain.Video
	Skipped bool
	Reason  string          // set when Skipped (e.g. "no transcript")
	Summary *domain.Summary // nil when Skipped
}

// ProcessNewVideo runs the core use case for a single video:
// resolve transcript -> (summarize -> deliver) | skip.
// See docs/use-cases/summarize_new_video.feature.
func (e *Engine) ProcessNewVideo(ctx context.Context, v domain.Video) (ProcessResult, error) {
	return ProcessResult{}, ErrNotImplemented
}