package config

import (
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"testing"
)

// TestReadmeNamesEverySetting checks that the list of settings in
// README.md names exactly the keys of the settings table, one item each.
// The list is the first one in the Configuration section, and it ends at
// the first blank line. Each item starts with its key in backticks.
func TestReadmeNamesEverySetting(t *testing.T) {
	t.Parallel()

	readme, err := os.ReadFile(filepath.Join("..", "..", "README.md"))
	if err != nil {
		t.Fatalf("failed to read README.md: %v", err)
	}

	_, section, found := strings.Cut(string(readme), "\n### Configuration\n")
	if !found {
		t.Fatal("README.md has no Configuration section")
	}

	// The section ends at the next heading of its level or above.
	section, _, _ = strings.Cut(section, "\n## ")
	section, _, _ = strings.Cut(section, "\n### ")

	_, list, found := strings.Cut(section, "\n- ")
	if !found {
		t.Fatal("README.md's Configuration section has no list")
	}

	list, _, _ = strings.Cut("- "+list, "\n\n")

	itemKey := regexp.MustCompile("^- `([^`]+)`")
	named := map[string]bool{}

	for line := range strings.SplitSeq(list, "\n") {
		// A line that does not start with "- " goes on with the item above.
		if !strings.HasPrefix(line, "- ") {
			continue
		}

		match := itemKey.FindStringSubmatch(line)
		if match == nil {
			t.Errorf("README.md's list of settings has an item "+
				"that does not start with a key in backticks: %s", line)

			continue
		}

		if named[match[1]] {
			t.Errorf("README.md's list of settings names %s twice", match[1])
		}

		named[match[1]] = true
	}

	for _, s := range new(Config).settings() {
		if !named[s.key] {
			t.Errorf("README.md's list of settings does not name %s", s.key)
		}

		delete(named, s.key)
	}

	for key := range named {
		t.Errorf("README.md's list of settings names %s, "+
			"which is not a setting", key)
	}
}

// TestExampleConfigNamesEverySetting checks that
// configs/config.example.yml names exactly the keys of the settings
// table, each one set or commented out with "# ". A key line holds the
// key, a colon and at most a one-word value, which tells it from a
// comment line that starts with a word and a colon. An indented key is
// inside the map of the key above it, as username is inside metrics.
func TestExampleConfigNamesEverySetting(t *testing.T) {
	t.Parallel()

	const examplePath = "configs/config.example.yml"

	example, err := os.ReadFile(filepath.Join("..", "..", examplePath))
	if err != nil {
		t.Fatalf("failed to read %s: %v", examplePath, err)
	}

	keyLine := regexp.MustCompile(`(?m)^(?:# )?( *)([a-z_]+):(?: \S+)?$`)
	named := map[string]bool{}

	var mapKey string

	for _, match := range keyLine.FindAllStringSubmatch(string(example), -1) {
		indent, key := match[1], match[2]
		if indent == "" {
			mapKey = key
			named[key] = true

			continue
		}

		// The key holding the map is not itself a setting.
		delete(named, mapKey)

		named[mapKey+"."+key] = true
	}

	// The env section sets environment variables; it is not a setting.
	delete(named, "env")

	for _, s := range new(Config).settings() {
		if !named[s.key] {
			t.Errorf("%s does not name %s", examplePath, s.key)
		}

		delete(named, s.key)
	}

	for key := range named {
		t.Errorf("%s names %s, which is not a setting", examplePath, key)
	}
}