package dev.getchat.sdk;

import java.time.Instant;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import org.jspecify.annotations.Nullable;

/**

* A typed, read-only view over a message returned by the REST API — the

* {@code MessageResource} shape in the backend's {@code openapi.yml}.

*

* <p>Like {@link ChatDetails}, this is a <strong>lazy view</strong> over the

* underlying {@link JsonValue}: accessors read on call and unknown fields stay

* reachable through {@link #raw()}.

*

* <h2>The sender</h2>

* <p>A {@code MessageResource} carries only the sender's external {@link #userId()},

* not an embedded user object. When a list request asks for {@code with_users}, the

* full user objects live in a sibling {@code users} map on the list envelope (keyed

* by the backend's <em>internal</em> id, which does not match the external

* {@code user_id}); reach it via {@code page.raw().get("users")}. There is no

* {@code user()} accessor here because the schema has no such field.

*

* <h2>Timestamps</h2>

* <p>Unlike {@link ChatDetails}, message timestamps are <strong>Unix epoch seconds</strong>

* (integers), not ISO strings; {@link #createdAt()} / {@link #updatedAt()} convert

* them to {@link Instant}. A non-numeric or absent value yields {@code null}

* ({@code updated_at} is null until the first edit).

*

* <h2>Null policy</h2>

* <ul>

* <li>{@link #id()} and {@link #userId()} are spec-required scalars, returned

* non-null (lenient empty string if the backend omits them).</li>

* <li>{@link #text()} is nullable (null for deleted messages) and

* {@link #recipientId()} is optional; both return {@code null} when absent.</li>

* <li>{@link #isDeleted()}, {@link #isEdited()}, {@link #seq()} and

* {@link #versions()} are spec-required and return primitives.</li>

* <li>{@link #extra()} is a chain-safe {@link JsonValue} — note the backend

* serialises an empty {@code extra} as a JSON array {@code []}, not

* {@code {}}.</li>

* </ul>

*

* <p>Two instances are equal when their underlying JSON is equal.

*/

public final class Message {

private final JsonValue raw;

private Message(JsonValue raw) {

this.raw = raw;

}

/** Wrap a message {@code JsonValue} (a {@code MessageResource} object) as a typed view. */

public static Message of(JsonValue raw) {

return new Message(raw);

}

/** The underlying JSON, for fields without a typed accessor. */

public JsonValue raw() {

return raw;

}

/** Message id (spec-required; lenient empty string if the backend omits it). */

public String id() {

return raw.get("id").asString("");

}

/** Monotonic per-chat sequence number — the sort key (0 if absent). */

public long seq() {

return raw.get("seq").asLong(0);

}

/**

* The sender's external id when known (the internal id for legacy messages

* without one); lenient empty string if the backend omits it.

*/

public String userId() {

return raw.get("user_id").asString("");

}

/** Message text, or {@code null} for a deleted message. */

public @Nullable String text() {

JsonValue v = raw.get("text");

return v.isString() ? v.asString() : null;

}

/** Creation time (from Unix epoch seconds), or {@code null} when absent/non-numeric. */

public @Nullable Instant createdAt() {

return epochSeconds(raw.get("created_at"));

}

/** Last-edit time (from Unix epoch seconds), or {@code null} until the first edit. */

public @Nullable Instant updatedAt() {

return epochSeconds(raw.get("updated_at"));

}

/** Whether the message is soft-deleted. */

public boolean isDeleted() {

return raw.get("is_deleted").asBoolean(false);

}

/** Whether the message has been edited. */

public boolean isEdited() {

return raw.get("is_edited").asBoolean(false);

}

/** Number of stored previous versions. */

public int versions() {

return raw.get("versions").asInt(0);

}

/**

* The message's {@code extra} fields as a chain-safe {@link JsonValue}. Note

* the backend serialises an empty {@code extra} as a JSON array {@code []}

* (not {@code {}}); {@link JsonValue#toMap()} still yields an empty map either

* way.

*/

public JsonValue extra() {

return raw.get("extra");

}

/** External recipient id, or {@code null} when unset. */

public @Nullable String recipientId() {

JsonValue v = raw.get("recipient_id");

return v.isString() ? v.asString() : null;

}

/**

* The message's inline buttons as typed {@link ButtonDetails}, in order.

* Unmodifiable and empty (never {@code null}) when the message has none.

*/

public List<ButtonDetails> buttons() {

List<JsonValue> values = raw.get("buttons").values();

List<ButtonDetails> out = new ArrayList<>(values.size());

for (JsonValue value : values) {

out.add(ButtonDetails.of(value));

}

return Collections.unmodifiableList(out);

}

private static @Nullable Instant epochSeconds(JsonValue value) {

if (!value.isNumber()) {

return null;

}

return Instant.ofEpochSecond(value.asLong(0));

}

/** Equal when the underlying JSON is equal. */

@Override

public boolean equals(@Nullable Object o) {

return this == o || (o instanceof Message other && raw.equals(other.raw));

}

@Override

public int hashCode() {

return raw.hashCode();

}

/** Compact summary for logs, e.g. {@code Message{id=m-1, seq=7, userId=u-1, deleted=false}}. */

@Override

public String toString() {

return "Message{id=" + id() + ", seq=" + seq() + ", userId=" + userId() + ", deleted=" + isDeleted() + "}";

}

}