package main

import (
	"context"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"
)

type roundTripFunc func(*http.Request) (*http.Response, error)

func (function roundTripFunc) RoundTrip(request *http.Request) (*http.Response, error) {
	return function(request)
}

func TestFetchSourceUsesValidatorsAndNotBefore(t *testing.T) {
	requests := 0
	client := &http.Client{Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
		requests++
		if request.Header.Get("If-None-Match") == `"generation-1"` {
			return &http.Response{StatusCode: http.StatusNotModified, Header: make(http.Header), Body: io.NopCloser(strings.NewReader(""))}, nil
		}
		header := make(http.Header)
		header.Set("ETag", `"generation-1"`)
		return &http.Response{StatusCode: http.StatusOK, Header: header, Body: io.NopCloser(strings.NewReader("source generation"))}, nil
	})}
	directory := t.TempDir()
	dataDirectory := filepath.Join(directory, "data")
	stateDirectory := filepath.Join(directory, "state")
	item := source{name: "source.txt", url: "https://source.example.invalid/feed", minimumInterval: time.Hour}
	now := time.Date(2026, 7, 12, 0, 0, 0, 0, time.UTC)
	changed, err := fetchSource(context.Background(), client, "source", item, dataDirectory, stateDirectory, now)
	if err != nil || !changed {
		t.Fatalf("initial fetch changed=%t err=%v", changed, err)
	}
	changed, err = fetchSource(context.Background(), client, "source", item, dataDirectory, stateDirectory, now.Add(30*time.Minute))
	if err != nil || changed {
		t.Fatalf("not-before fetch changed=%t err=%v", changed, err)
	}
	changed, err = fetchSource(context.Background(), client, "source", item, dataDirectory, stateDirectory, now.Add(2*time.Hour))
	if err != nil || changed {
		t.Fatalf("conditional fetch changed=%t err=%v", changed, err)
	}
	if requests != 2 {
		t.Fatalf("requests=%d, want 2", requests)
	}
	contents, err := os.ReadFile(filepath.Join(dataDirectory, "source.txt"))
	if err != nil || string(contents) != "source generation" {
		t.Fatalf("cached source=%q err=%v", contents, err)
	}
}

func TestFetchSourcePersistsRetryFloor(t *testing.T) {
	requests := 0
	client := &http.Client{Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
		requests++
		header := make(http.Header)
		header.Set("Retry-After", "3600")
		return &http.Response{StatusCode: http.StatusTooManyRequests, Header: header, Body: io.NopCloser(strings.NewReader(""))}, nil
	})}
	directory := t.TempDir()
	dataDirectory := filepath.Join(directory, "data")
	stateDirectory := filepath.Join(directory, "state")
	if err := os.MkdirAll(dataDirectory, 0o700); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dataDirectory, "source.txt"), []byte("cached"), 0o600); err != nil {
		t.Fatal(err)
	}
	if err := writeState(filepath.Join(stateDirectory, "source.json"), sourceState{SHA256: "cached-generation"}); err != nil {
		t.Fatal(err)
	}
	item := source{name: "source.txt", url: "https://source.example.invalid/feed", minimumInterval: time.Hour}
	now := time.Date(2026, 7, 12, 0, 0, 0, 0, time.UTC)
	if _, err := fetchSource(context.Background(), client, "source", item, dataDirectory, stateDirectory, now); err == nil {
		t.Fatal("expected rate-limit error")
	}
	changed, err := fetchSource(context.Background(), client, "source", item, dataDirectory, stateDirectory, now.Add(time.Minute))
	if err != nil || changed {
		t.Fatalf("retry-floor fetch changed=%t err=%v", changed, err)
	}
	if requests != 1 {
		t.Fatalf("requests=%d, want 1", requests)
	}
}