Daft.ie email parser

Implemented in DaftAlerts.Infrastructure/Parsing/DaftEmailParser.cs. Turns an HTML alert email body into a ParsedDaftEmail DTO.

Contract

public interface IDaftEmailParser
{
    ParsedDaftEmail? Parse(string htmlBody, string subject, DateTime receivedAt, string? messageId);
}

Returns null if parsing fails to produce a viable result — specifically if there is no DaftId (required for idempotency) or no price. All other fields degrade gracefully to null or defaults when missing.

What it extracts

Field	How it’s found
DaftId	Regex over every <a> tag’s originalsrc and href (after SafeLinks unwrap): daft\.ie/for-rent/[^/?#]+/(\d+).
DaftUrl	Same match, unwrapped from Outlook SafeLinks if present.
Address	First element with css-class="address" attribute. Falls back to the line containing the Eircode.
Eircode	Regex [ADCEFHKNPRTVWXY]\d{2}\s?[A-Z0-9]{4} applied to the address or full body. Normalized to uppercase, no spaces.
RoutingKey	First 3 characters of the normalized Eircode.
PriceMonthly	Regex €\s*([\d,]+(?:\.\d{2})?)\s*per\s*month on subject first, body as fallback.
Beds	Regex (\d+)\s*Bed\b on body text.
Baths	Regex (\d+)\s*Bath\b on body text.
PropertyType	Substring match on subject: House, Apartment, Studio, Shared. Falls back to body text; defaults to “Other”.
BerRating	Regex /ber/([A-G]\d?|Exempt)\.png on any <img src>.
MainImageUrl	First <img> whose src contains media.daft.ie.

Outlook SafeLinks unwrapping

Outlook wraps outgoing links as https://<tenant>.safelinks.protection.outlook.com/?url=ENCODED&data=.... The parser:

1. Checks the originalsrc attribute first — Outlook sets this to the pre-wrap URL.
2. If only href is present, it looks for the safelinks host. If found, it parses the query string, takes the url parameter, URL-decodes it, and uses that as the real URL.

See DaftEmailParser.UnwrapSafeLink for the implementation.

Graceful degradation

• No Eircode present → Eircode and RoutingKey are both null. The property still shows in the inbox but won’t be matched by routing-key filters.
• No BER image → BerRating is null. BER-minimum filter passes this property through (null is treated as “unknown but not disqualifying”).
• No main image → MainImageUrl is null. Frontend falls back to a placeholder.
• Malformed HTML → HtmlAgilityPack’s tolerant parser handles most issues; OptionAutoCloseOnEnd and OptionFixNestedTags are enabled.

Adding a new variant

When Daft changes their template (or a new email layout appears, like Daft Sharing), the workflow is:

1. Capture a real sample email. Save it as tests/DaftAlerts.Infrastructure.Tests/TestData/sample-<variant>.eml.
2. Add a new [Fact] in DaftEmailParserTests.cs that asserts every field.
3. Run the tests. See what fails.
4. Adjust DaftEmailParser.cs — typically a new regex pattern, a new CSS selector, or a new link-walking branch.
5. Re-run the existing tests to make sure no prior variant regressed.

Because the parser is pure (takes string, returns ParsedDaftEmail), every variant is trivial to reproduce in a test. Don’t skip step 3 — it’s how you avoid breaking other variants.

Re-running the parser over historical emails

Raw MIME bytes are stored in RawEmails.RawMimeBytes for 90 days (configurable). The ParseRetryWorker automatically retries rows with ParseStatus=Failed every 30 minutes.

To force a retry of a specific email:

UPDATE RawEmails SET ParseStatus = 2 /* Failed */, LastAttemptAt = NULL WHERE Id = <id>;

Within 30 minutes the worker will pick it up.

Known limitations

• Subject-based property type detection can be fooled if the address contains the word “House” or “Apartment”. In practice Daft’s subject format is structured enough that this hasn’t come up.
• Multi-listing emails — if a single email contains multiple listings, only the first one is parsed. The pipeline would need a list-returning overload. Not a current use case; worth watching for.
• Non-Euro pricing — the regex hardcodes €. All current Daft.ie pricing is euro; revisit if that changes.
• originalsrc on non-Outlook clients — Outlook SafeLinks sets originalsrc on <a> tags. Other clients don’t wrap links at all, so href just works. No other client’s wrapping format is handled today.