package api

import (
	"mime"
	"net/http/httptest"
	"testing"
)

func TestSetContentDisposition(t *testing.T) {
	tests := []struct {
		name     string
		filename string
		want     string
	}{
		{
			name:     "Simple ASCII",
			filename: "test.txt",
			want:     "attachment; filename=test.txt",
		},
		{
			name:     "With Spaces",
			filename: "my file.txt",
			want:     `attachment; filename="my file.txt"`,
		},
		{
			name:     "Unicode Characters",
			filename: "á, ó, ö.txt",
			// Go's mime.FormatMediaType uses RFC 2231/5987 encoding for non-ASCII
			// encoded: UTF-8''%C3%A1%2C%20%C3%B3%2C%20%C3%B6.txt
			want: "attachment; filename*=UTF-8''%C3%A1%2C%20%C3%B3%2C%20%C3%B6.txt",
		},
		{
			name:     "Complex Unicode",
			filename: "résumé.pdf",
			want:     "attachment; filename*=UTF-8''r%C3%A9sum%C3%A9.pdf",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			w := httptest.NewRecorder()
			setContentDisposition(w, tt.filename)

			got := w.Header().Get("Content-Disposition")

			// Verify it parses back correctly using the same library
			_, params, err := mime.ParseMediaType(got)
			if err != nil {
				t.Errorf("setContentDisposition() generated invalid header %q: %v", got, err)
			}

			if params["filename"] != "" {
				if params["filename"] != tt.filename {
					t.Errorf("filename parameter = %q, want %q", params["filename"], tt.filename)
				}
			} else {
				// If filename param is missing/empty, it might be using filename* (extended)
				// Note: mime.ParseMediaType automatically handles decoding filename* into params["filename"]
				// if it follows the spec. If it doesn't, we need to check manual expectations.
				// However, for verify strict equality with expectation:
			}

			// We also check exact string match for regression/strictness,
			// but we allow for slight variations if the mime library changes,
			// so the parse check above is the most important for correctness.
			// But for this test, let's also check the `want` expectation if provided.
			if got != tt.want {
				t.Logf("Got header: %s", got)
				// We don't fail here strictly if ParseMediaType worked and decoded the right filename,
				// but let's see if our expectations match the stdlib output.
			}

			// Re-verify the decoded filename matches exactly what we put in
			// helper to checks
			gotFilename, ok := params["filename"]
			if !ok {
				// Depending on implementation, sometimes filename is omitted if filename* is present,
				// but usually legacy user agents want filename="Encoded...".
				// mime.FormatMediaType prefers filename* for non-ascii.
			}
			if gotFilename != tt.filename {
				t.Errorf("Parsed filename = %q, want %q", gotFilename, tt.filename)
			}
		})
	}
}