// FILE: ./internal/sources/common/http_source.go
package common

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"

	"gitea.maximumdirect.net/ejr/feedkit/config"
	"gitea.maximumdirect.net/ejr/feedkit/transport"
)

// HTTPSource is a tiny, reusable "HTTP polling spine" for weatherfeeder sources.
//
// It centralizes the boring parts:
//   - standard config shape (url + user_agent) via RequireHTTPSourceConfig
//   - a default http.Client with timeout
//   - FetchBody / headers / max-body safety limit
//   - consistent error wrapping (driver + source name)
//
// Individual drivers remain responsible for:
//   - decoding minimal metadata (for Event.ID / EffectiveAt)
//   - constructing the event envelope (kind/schema/payload)
type HTTPSource struct {
	Driver    string
	Name      string
	URL       string
	UserAgent string
	Accept    string
	Client    *http.Client
}

// NewHTTPSource builds an HTTPSource using weatherfeeder's standard HTTP source
// config (params.url + params.user_agent) and a default HTTP client.
func NewHTTPSource(driver string, cfg config.SourceConfig, accept string) (*HTTPSource, error) {
	c, err := RequireHTTPSourceConfig(driver, cfg)
	if err != nil {
		return nil, err
	}

	return &HTTPSource{
		Driver:    driver,
		Name:      c.Name,
		URL:       c.URL,
		UserAgent: c.UserAgent,
		Accept:    accept,
		Client:    transport.NewHTTPClient(transport.DefaultHTTPTimeout),
	}, nil
}

// FetchBytes fetches the URL and returns the raw response body bytes.
func (s *HTTPSource) FetchBytes(ctx context.Context) ([]byte, error) {
	client := s.Client
	if client == nil {
		// Defensive: allow tests or callers to nil out Client; keep behavior sane.
		client = transport.NewHTTPClient(transport.DefaultHTTPTimeout)
	}

	b, err := transport.FetchBody(ctx, client, s.URL, s.UserAgent, s.Accept)
	if err != nil {
		return nil, fmt.Errorf("%s %q: %w", s.Driver, s.Name, err)
	}
	return b, nil
}

// FetchJSON fetches the URL and returns the raw body as json.RawMessage.
// json.Unmarshal accepts json.RawMessage directly, so callers can decode minimal
// metadata without keeping both []byte and RawMessage in their own structs.
func (s *HTTPSource) FetchJSON(ctx context.Context) (json.RawMessage, error) {
	b, err := s.FetchBytes(ctx)
	if err != nil {
		return nil, err
	}
	return json.RawMessage(b), nil
}