use crate::user_discovery::stores::InMemoryStore;
use crate::user_discovery::traits::tests::TestingUtils;
use crate::user_discovery::{UserDiscovery, UserDiscoveryStore, UserDiscoveryVersion, UserID};
use prost::Message;
use rand::seq::SliceRandom;
use std::collections::{HashMap, HashSet};
use std::vec;

struct TestNetwork<S: UserDiscoveryStore> {
    ids_by_name: HashMap<&'static str, usize>,
    names: Vec<&'static str>,
    friends: Vec<Vec<usize>>,
    message_flows: Vec<(usize, usize)>,
    announced_users_expected: Vec<Vec<(usize, Vec<usize>)>>,
    uds: Vec<UserDiscovery<S, TestingUtils>>,
}

impl<S: UserDiscoveryStore + Clone + Default> TestNetwork<S> {
    fn new() -> Self {
        Self {
            ids_by_name: HashMap::new(),
            names: vec![],
            friends: vec![],
            message_flows: vec![],
            announced_users_expected: vec![],
            uds: vec![],
        }
    }

    async fn add_user(&mut self, name: &'static str, threshold: u8) {
        let id = self.names.len();
        self.ids_by_name.insert(name, id);
        self.names.push(name);
        self.friends.push(vec![]);
        self.announced_users_expected.push(vec![]);

        let store = S::default();
        self.uds.push(get_ud(id, threshold, store).await);
    }

    fn set_friends(&mut self, user: &str, friends: &[&str]) {
        let id = self.ids_by_name[user];
        let f_ids: Vec<usize> = friends.iter().map(|f| self.ids_by_name[*f]).collect();
        self.friends[id] = f_ids;
    }

    fn add_message_flow(&mut self, user: &str, count: usize) {
        let id = self.ids_by_name[user];
        self.message_flows.push((id, count));
    }

    fn expect_announced_user(&mut self, user: &str, contact: &str, friends_of_contact: &[&str]) {
        let user_id = self.ids_by_name[user];
        let contact_id = self.ids_by_name[contact];
        let f_ids: Vec<usize> = friends_of_contact
            .iter()
            .map(|f| self.ids_by_name[*f])
            .collect();
        self.announced_users_expected[user_id].push((contact_id, f_ids));
    }
}

async fn get_with_five_users<S: UserDiscoveryStore + Default + Clone>() -> TestNetwork<S> {
    let mut network = TestNetwork::new();

    network.add_user("ALICE", 2).await;
    network.add_user("BOB", 2).await;
    network.add_user("CHARLIE", 2).await;
    network.add_user("DAVID", 2).await;
    network.add_user("FRANK", 2).await;

    network.set_friends("ALICE", &["BOB", "CHARLIE"]);
    network.set_friends("BOB", &["ALICE", "CHARLIE", "DAVID"]);
    network.set_friends("CHARLIE", &["ALICE", "BOB", "DAVID", "FRANK"]);
    network.set_friends("DAVID", &["BOB", "CHARLIE"]);
    network.set_friends("FRANK", &["CHARLIE"]);

    network.add_message_flow("ALICE", 1); // ALICE: own announcement sending to BOB and CHARLIE
    network.add_message_flow("BOB", 2); // BOB: own announcement + promotion for ALICE
    network.add_message_flow("BOB", 0); // BOBs version should not have any new messages for his friends
    network.add_message_flow("ALICE", 1); // ALICE: promotion for BOB
    network.add_message_flow("CHARLIE", 3); // CHARLIE: own announcement + promotion for ALICE, BOB
    network.add_message_flow("DAVID", 3); // DAVID: own announcement + promotion for BOB, CHARLIE
    network.add_message_flow("BOB", 2); // BOB: promotion for CHARLIE, DAVID
    network.add_message_flow("CHARLIE", 1); // CHARLIE: promotion for DAVID
    network.add_message_flow("FRANK", 2); // FRANK: own announcement +  promotion for CHARLIE
    network.add_message_flow("CHARLIE", 1); // CHARLIE: promotion for FRANK
    network.add_message_flow("ALICE", 1); // ALICE: promotion for CHARLIE

    // ALICE should now know that BOB and CHARLIE, BOB and DAVID and CHARLIE and DAVID are friends.
    // Alice should also have one protected share from Frank.
    network.expect_announced_user("ALICE", "BOB", &["CHARLIE"]); // ALICE knows Bob and that CHARLIE is connected with BOB
    network.expect_announced_user("ALICE", "CHARLIE", &["BOB"]); // ALICE knows CHARLIE and that BOB is connected with CHARLIE
    network.expect_announced_user("ALICE", "DAVID", &["BOB", "CHARLIE"]); // ALICE knows DAVID and that BOB and CHARLIE are connected with DAVID

    network.expect_announced_user("BOB", "ALICE", &["CHARLIE"]);
    network.expect_announced_user("BOB", "CHARLIE", &["ALICE", "DAVID"]);
    network.expect_announced_user("BOB", "DAVID", &["CHARLIE"]);

    network.expect_announced_user("CHARLIE", "ALICE", &["BOB"]);
    network.expect_announced_user("CHARLIE", "BOB", &["ALICE", "DAVID"]);
    network.expect_announced_user("CHARLIE", "DAVID", &["BOB"]);
    network.expect_announced_user("CHARLIE", "FRANK", &[]);

    network.expect_announced_user("DAVID", "ALICE", &["BOB", "CHARLIE"]);
    network.expect_announced_user("DAVID", "BOB", &["CHARLIE"]);
    network.expect_announced_user("DAVID", "CHARLIE", &["BOB"]);

    network.expect_announced_user("FRANK", "CHARLIE", &[]);

    network
}

#[tokio::test]
async fn test_user_discovery_decreased_threshold_in_memory_store() {
    let _ = pretty_env_logger::try_init();

    let mut network = TestNetwork::<InMemoryStore>::new();

    // Start ALICE with a more strict threshold of 3.
    // David only has 2 paths to Alice (via Bob and Charlie). Since 2 < 3, David cannot discover Alice.
    network.add_user("ALICE", 3).await;
    network.add_user("BOB", 2).await;
    network.add_user("CHARLIE", 2).await;
    network.add_user("DAVID", 2).await;
    network.add_user("FRANK", 2).await;

    // Same topology as the initial 5 users
    network.set_friends("ALICE", &["BOB", "CHARLIE"]);
    network.set_friends("BOB", &["ALICE", "CHARLIE", "DAVID"]);
    network.set_friends("CHARLIE", &["ALICE", "BOB", "DAVID", "FRANK"]);
    network.set_friends("DAVID", &["BOB", "CHARLIE"]);
    network.set_friends("FRANK", &["CHARLIE"]);

    let david_idx = network.ids_by_name["DAVID"];
    let alice_idx = network.ids_by_name["ALICE"];
    let charlie_idx = network.ids_by_name["CHARLIE"];

    // Phase 1: Exchange with ALICE threshold = 3
    step0_exchange_random::<InMemoryStore>(&network).await;
    step1_verify_no_new_messages::<InMemoryStore>(&network).await;

    let version = network.uds[david_idx]
        .get_contact_version(charlie_idx as UserID)
        .await
        .unwrap()
        .unwrap();
    assert_eq!(version, get_version_bytes(1, 4));

    // DAVID should NOT know ALICE yet because ALICE's threshold is 3, but David only has 2 shares.
    let david_knows = network.uds[david_idx]
        .get_all_announced_users()
        .await
        .unwrap();

    let knows_alice = david_knows
        .iter()
        .any(|(u, _)| u.user_id == alice_idx as UserID);

    assert!(!knows_alice, "David should not know Alice yet because Alice's threshold is 3 and David only receives 2 shares");

    // Phase 2: Update ALICE's threshold to 2
    network.uds[alice_idx]
        .initialize_or_update(2, alice_idx as UserID, vec![alice_idx as u8; 32])
        .await
        .unwrap();

    let version = network.uds[alice_idx].get_current_version().await.unwrap();
    assert_eq!(version, get_version_bytes(2, 2));

    // ALICE's new announcement with threshold 2 should propagate further.
    step0_exchange_random::<InMemoryStore>(&network).await;
    step1_verify_no_new_messages::<InMemoryStore>(&network).await;

    let version = network.uds[david_idx]
        .get_contact_version(charlie_idx as UserID)
        .await
        .unwrap()
        .unwrap();
    assert_eq!(version, get_version_bytes(1, 5));

    let version = network.uds[alice_idx].get_current_version().await.unwrap();
    assert_eq!(version, get_version_bytes(2, 2));

    // Now DAVID SHOULD know ALICE
    let david_knows = network.uds[david_idx]
        .get_all_announced_users()
        .await
        .unwrap();
    let knows_alice_now = david_knows
        .iter()
        .any(|(u, _)| u.user_id == alice_idx as UserID);
    assert!(
        knows_alice_now,
        "David should know Alice now because her threshold was updated to 2"
    );
}

#[tokio::test]
async fn test_user_discovery_increased_threshold_in_memory_store() {
    let _ = pretty_env_logger::try_init();

    let mut network = TestNetwork::<InMemoryStore>::new();

    // Start ALICE with a more strict threshold of 3.
    // David only has 2 paths to Alice (via Bob and Charlie). Since 2 < 3, David cannot discover Alice.
    network.add_user("ALICE", 2).await;
    network.add_user("BOB", 2).await;
    network.add_user("CHARLIE", 2).await;
    network.add_user("DAVID", 2).await;
    network.add_user("FRANK", 2).await;

    // Same topology as the initial 5 users
    network.set_friends("ALICE", &["BOB", "CHARLIE"]);
    network.set_friends("BOB", &["ALICE", "CHARLIE", "DAVID"]);
    // CHARLIE IS NOT YET A FRIEND OF DAVID -> DAVID SHOULD NOT BE ABLE TO BE DECODE ALICE
    network.set_friends("CHARLIE", &["ALICE", "BOB", "FRANK"]);
    network.set_friends("DAVID", &["BOB", "CHARLIE"]);
    network.set_friends("FRANK", &["CHARLIE"]);

    let david_idx = network.ids_by_name["DAVID"];
    let alice_idx = network.ids_by_name["ALICE"];

    // Phase 1: Exchange with ALICE threshold = 2
    step0_exchange_random::<InMemoryStore>(&network).await;
    step1_verify_no_new_messages::<InMemoryStore>(&network).await;

    // DAVID should NOT know ALICE yet because ALICE's threshold is 2, and David has only 1 shares.
    {
        let david_knows = network.uds[david_idx]
            .get_all_announced_users()
            .await
            .unwrap();

        let knows_alice = david_knows
            .iter()
            .any(|(u, _)| u.user_id == alice_idx as UserID);

        assert!(!knows_alice, "David should not know Alice yet because Alice's threshold is 3 and David only receives 2 shares");
    }

    // Phase 2: Update ALICE's threshold to 3
    network.uds[alice_idx]
        .initialize_or_update(3, alice_idx as UserID, vec![alice_idx as u8; 32])
        .await
        .unwrap();

    // ALICE's new announcement with threshold 3 should propagate further.
    // This SHOULD REPLACE THE OLD VERSION...
    step0_exchange_random::<InMemoryStore>(&network).await;
    step1_verify_no_new_messages::<InMemoryStore>(&network).await;

    // Now Charlie is a friend of David, so he should exchange ALICE with him

    network.set_friends("CHARLIE", &["ALICE", "BOB", "DAVID", "FRANK"]);

    // ALICE's new announcement with threshold 3 should propagate further.
    // This SHOULD REPLACE THE OLD VERSION...
    step0_exchange_random::<InMemoryStore>(&network).await;
    step1_verify_no_new_messages::<InMemoryStore>(&network).await;

    // DAVID should still NOT know ALICE yet because ALICE's new threshold is 3, and David has only 2 shares.
    {
        let david_knows = network.uds[david_idx]
            .get_all_announced_users()
            .await
            .unwrap();

        let knows_alice = david_knows
            .iter()
            .any(|(u, _)| u.user_id == alice_idx as UserID);

        assert!(!knows_alice, "David should not know Alice yet because Alice's threshold is 3 and David only receives 2 shares");
    }
}

#[tokio::test]
async fn test_user_discovery_in_memory_store() {
    let _ = pretty_env_logger::try_init();

    let users = get_with_five_users().await;
    step0_exchange_in_order::<InMemoryStore>(&users).await;
    step1_verify_no_new_messages::<InMemoryStore>(&users).await;
    step2_verify_announced_users_expected::<InMemoryStore>(&users).await;

    let alice_idx = users.ids_by_name["ALICE"];
    let bob_idx = users.ids_by_name["BOB"];
    let david_idx = users.ids_by_name["DAVID"];

    users.uds[bob_idx]
        .update_verification_state_for_user(alice_idx as UserID, Some(10))
        .await
        .unwrap();

    step0_exchange_random::<InMemoryStore>(&users).await;
    step1_verify_no_new_messages::<InMemoryStore>(&users).await;

    {
        let david_knows = users.uds[david_idx]
            .get_all_announced_users()
            .await
            .unwrap();

        let knows_alice = david_knows
            .iter()
            .find(|(u, _)| u.user_id == alice_idx as UserID);

        assert!(knows_alice.is_some(), "David should know Alice");

        let bob_has_verified = knows_alice
            .unwrap()
            .1
            .iter()
            .find(|(user_id, _)| *user_id == bob_idx as UserID)
            .unwrap();

        assert_eq!(bob_has_verified.1, Some(10));
    }
}

#[tokio::test]
async fn test_user_discovery_random_order_in_memory_store() {
    let _ = pretty_env_logger::try_init();

    let users = get_with_five_users().await;
    step0_exchange_random::<InMemoryStore>(&users).await;
    step1_verify_no_new_messages::<InMemoryStore>(&users).await;
    step2_verify_announced_users_expected::<InMemoryStore>(&users).await;
}

async fn step0_exchange_in_order<S: UserDiscoveryStore + Clone + Default>(users: &TestNetwork<S>) {
    for (i, (from, count)) in users.message_flows.iter().enumerate() {
        tracing::debug!("MESSAGE FLOW: {i}");
        to_all_friends(*from, *count, &users).await;
    }
}

async fn step0_exchange_random<S: UserDiscoveryStore + Clone + Default>(users: &TestNetwork<S>) {
    let mut user_ids: Vec<usize> = (0..users.names.len()).collect();

    for _ in 0..100 {
        user_ids.shuffle(&mut rand::rng());

        for from in user_ids.clone() {
            for friend in &users.friends[from] {
                request_and_handle_messages(
                    (from, &users.uds[from]),
                    (*friend, &users.uds[*friend]),
                    None,
                )
                .await;
            }
        }
    }
}

async fn step1_verify_no_new_messages<S: UserDiscoveryStore + Clone + Default>(
    users: &TestNetwork<S>,
) {
    tracing::debug!("Now all users should have the newest version.");

    for from in 0..users.names.len() {
        for to in &users.friends[from] {
            tracing::debug!(
                "Does {} has open messages for {}?",
                &users.names[from],
                &users.names[*to]
            );
            assert_new_messages((from, &users.uds[from]), (*to, &users.uds[*to]), false).await;
        }
    }
}

async fn step2_verify_announced_users_expected<S: UserDiscoveryStore + Clone + Default>(
    users: &TestNetwork<S>,
) {
    tracing::debug!("Test if all exchanges where successful.");

    for (user, announcements) in users.announced_users_expected.iter().enumerate() {
        let announced_users2 = users.uds[user].get_all_announced_users().await.unwrap();
        let mut announced_users = HashMap::new();
        for a in announced_users2 {
            announced_users.insert(a.0.user_id, a.1.iter().map(|x| x.0).collect::<Vec<_>>());
        }
        tracing::debug!("{} knows now: {}", users.names[user], announced_users.len());
        assert_eq!(announced_users.len(), announcements.len());
        for (contact_id, announced_users_expected) in announcements {
            let announced_users = announced_users.get(&(*contact_id as i64)).unwrap();
            tracing::debug!(
                "{} knows now that {} has the following friends: {}",
                users.names[user],
                users.names[*contact_id],
                announced_users
                    .iter()
                    .map(|x| users.names[*x as usize])
                    .collect::<Vec<_>>()
                    .join(", ")
            );
            let announced_users: HashSet<i64> = announced_users.iter().cloned().collect();
            let announced_users_expected: HashSet<i64> = announced_users_expected
                .iter()
                .cloned()
                .map(|x| x as i64)
                .collect();
            assert_eq!(announced_users, announced_users_expected);
        }
    }
}

async fn get_ud<S: UserDiscoveryStore + Clone + Default>(
    user_id: usize,
    threshold: u8,
    store: S,
) -> UserDiscovery<S, TestingUtils> {
    let ud = UserDiscovery::new(store.to_owned(), TestingUtils::default()).unwrap();

    ud.initialize_or_update(threshold, user_id as UserID, vec![user_id as u8; 32])
        .await
        .unwrap();

    let version = ud.get_current_version().await.unwrap();

    assert_eq!(version, get_version_bytes(1, 0));
    ud
}

async fn assert_new_messages<S: UserDiscoveryStore>(
    from: (usize, &UserDiscovery<S, TestingUtils>),
    to: (usize, &UserDiscovery<S, TestingUtils>),
    has_new_messages: bool,
) {
    // From sends a message with his current version to To
    let to_received_version = &from.1.get_current_version().await.unwrap();
    assert_eq!(
        to.1.should_request_new_messages(from.0 as UserID, to_received_version)
            .await
            .unwrap()
            .is_some(),
        has_new_messages
    );
}

async fn request_and_handle_messages<S: UserDiscoveryStore>(
    from: (usize, &UserDiscovery<S, TestingUtils>),
    to: (usize, &UserDiscovery<S, TestingUtils>),
    messages_count: Option<usize>,
) {
    // From sends a message with his current version to To

    if messages_count.is_some() {
        let to_received_version = &from.1.get_current_version().await.unwrap();
        assert_eq!(
            to.1.should_request_new_messages(from.0 as UserID, to_received_version)
                .await
                .unwrap()
                .is_some(),
            true
        );
    }

    // As To has a older version stored he sends a request to From: Give me all messages since version.
    let from_request_version_from_to =
        to.1.get_contact_version(from.0 as UserID)
            .await
            .unwrap()
            .unwrap_or(get_version_bytes(0, 0));

    let new_messages = from
        .1
        .get_new_messages(to.0 as UserID, &from_request_version_from_to)
        .await
        .unwrap();

    if let Some(messages_count) = messages_count {
        assert!(new_messages.len() <= messages_count);
    }

    to.1.handle_new_messages(from.0 as UserID, None, new_messages)
        .await
        .unwrap();

    if messages_count.is_some() {
        assert_eq!(
            to.1.should_request_new_messages(
                from.0 as UserID,
                &from.1.get_current_version().await.unwrap()
            )
            .await
            .unwrap()
            .is_some(),
            false
        );
    }
}

async fn to_all_friends<S: UserDiscoveryStore + Clone>(
    from: usize,
    message_count: usize,
    users: &TestNetwork<S>,
) {
    for friend in &users.friends[from] {
        tracing::debug!("From {} to {}", users.names[from], users.names[*friend]);

        if message_count == 0 {
            assert_new_messages(
                (from, &users.uds[from]),
                (*friend, &users.uds[*friend]),
                false,
            )
            .await;
        } else {
            request_and_handle_messages(
                (from, &users.uds[from]),
                (*friend, &users.uds[*friend]),
                Some(message_count),
            )
            .await;
        }
    }
}

fn get_version_bytes(announcement: u32, promotion: u32) -> Vec<u8> {
    UserDiscoveryVersion {
        announcement,
        promotion,
    }
    .encode_to_vec()
}