package autocorrect

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

func TestLoadValidRules(t *testing.T) {
	dir := t.TempDir()
	path := writeAutocorrect(t, dir, `autocorrect:
  - target: "Hrank"
    match:
      - "Frank"
      - "frank"
`)

	rules, err := Load(path)
	if err != nil {
		t.Fatalf("load rules: %v", err)
	}

	got, count := rules.Apply("Frank and frank")
	if got != "Hrank and Hrank" {
		t.Fatalf("text = %q, want %q", got, "Hrank and Hrank")
	}
	if count != 2 {
		t.Fatalf("count = %d, want 2", count)
	}
}

func TestLoadValidation(t *testing.T) {
	tests := []struct {
		name    string
		content string
		want    string
	}{
		{
			name:    "missing top-level autocorrect",
			content: `other: []`,
			want:    "must contain at least one autocorrect rule",
		},
		{
			name:    "empty rules list",
			content: `autocorrect: []`,
			want:    "must contain at least one autocorrect rule",
		},
		{
			name: "empty target",
			content: `autocorrect:
  - target: ""
    match: ["Frank"]
`,
			want: "must include target",
		},
		{
			name: "empty match list",
			content: `autocorrect:
  - target: "Hrank"
    match: []
`,
			want: "must include at least one match string",
		},
		{
			name: "empty match string",
			content: `autocorrect:
  - target: "Hrank"
    match: [" "]
`,
			want: "contains empty match string",
		},
		{
			name: "duplicate match across rules",
			content: `autocorrect:
  - target: "Hrank"
    match: ["Frank"]
  - target: "Other"
    match: ["Frank"]
`,
			want: `appears in both rule 0 and rule 1`,
		},
		{
			name: "duplicate match within rule",
			content: `autocorrect:
  - target: "Hrank"
    match: ["Frank", "Frank"]
`,
			want: `contains duplicate match string "Frank"`,
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			dir := t.TempDir()
			path := writeAutocorrect(t, dir, test.content)

			_, err := Load(path)
			if err == nil {
				t.Fatal("expected error")
			}
			if !strings.Contains(err.Error(), test.want) {
				t.Fatalf("expected error to contain %q, got %v", test.want, err)
			}
		})
	}
}

func TestApplyReplacementBehavior(t *testing.T) {
	rules := Rules{rules: []Rule{
		{
			Target: "Hrank",
			Match:  []string{"Frank"},
		},
		{
			Target: "Mike Brown",
			Match:  []string{"Mike Pat"},
		},
		{
			Target: "Godfrey",
			Match:  []string{"God-free"},
		},
	}}

	tests := []struct {
		name      string
		input     string
		want      string
		wantCount int
	}{
		{
			name:      "case sensitive",
			input:     "Frank and FRANK",
			want:      "Hrank and FRANK",
			wantCount: 1,
		},
		{
			name:      "punctuation boundary",
			input:     "Frank, are you there?",
			want:      "Hrank, are you there?",
			wantCount: 1,
		},
		{
			name:      "no substring in larger token",
			input:     "Franklin and xFrank Frank_y Frank2",
			want:      "Franklin and xFrank Frank_y Frank2",
			wantCount: 0,
		},
		{
			name:      "multi word match",
			input:     "Hello Mike Pat.",
			want:      "Hello Mike Brown.",
			wantCount: 1,
		},
		{
			name:      "hyphenated match",
			input:     "God-free is here.",
			want:      "Godfrey is here.",
			wantCount: 1,
		},
		{
			name:      "hyphen outside match is boundary",
			input:     "x-Frank-y",
			want:      "x-Hrank-y",
			wantCount: 1,
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			got, count := rules.Apply(test.input)
			if got != test.want {
				t.Fatalf("text = %q, want %q", got, test.want)
			}
			if count != test.wantCount {
				t.Fatalf("count = %d, want %d", count, test.wantCount)
			}
		})
	}
}

func writeAutocorrect(t *testing.T, dir string, content string) string {
	t.Helper()

	path := filepath.Join(dir, "autocorrect.yml")
	if err := os.WriteFile(path, []byte(content), 0o600); err != nil {
		t.Fatalf("write autocorrect file: %v", err)
	}
	return path
}