use hyper::{body::Bytes, header::HeaderValue, Body, Response};

use lox_library::{
    bridge_table::{BridgeLine, EncryptedBucket, MAX_BRIDGES_PER_BUCKET},
    proto::{
        blockage_migration, check_blockage, issue_invite, level_up, migration, open_invite,
        redeem_invite, trust_promotion,
    },
    BridgeAuth, BridgeDb, ExceededMaxBridgesError, IssuerPubKey, MAX_DAILY_BRIDGES,
};
use rdsys_backend::proto::{Resource, ResourceState};
use serde::{Deserialize, Serialize};

use std::{
    cmp::Ordering,
    collections::HashMap,
    sync::{Arc, Mutex},
};
use zkp::ProofError;

use crate::metrics::Metrics;
use crate::resource_parser::{parse_into_bridgelines, sort_for_parsing};

#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct LoxServerContext {
    pub db: Arc<Mutex<BridgeDb>>,
    pub ba: Arc<Mutex<BridgeAuth>>,
    pub extra_bridges: Arc<Mutex<Vec<BridgeLine>>>,
    pub to_be_replaced_bridges: Arc<Mutex<Vec<BridgeLine>>>,
    #[serde(skip)]
    pub metrics: Metrics,
}

impl LoxServerContext {
    pub fn bridgetable_is_empty(&self) -> bool {
        let mut ba_obj = self.ba.lock().unwrap();
        ba_obj.is_empty()
    }

    // Populate an empty bridgetable for the first time
    pub fn populate_bridgetable(
        &self,
        buckets: Vec<[BridgeLine; MAX_BRIDGES_PER_BUCKET]>,
        percent_spares: i32,
    ) {
        let mut partition: i32 = 0;
        if percent_spares != 0 {
            partition = buckets.len() as i32 * percent_spares / 100;
        }
        let (spares, open_invitations) = buckets.split_at(partition as usize);
        for bucket in spares {
            self.add_spare_bucket(*bucket)
        }

        for bucket in open_invitations {
            self.add_openinv_bucket(*bucket)
        }
    }

    pub fn handle_working_resources(&self, working_resources: Vec<Resource>) -> Vec<u64> {
        let mut accounted_for_bridges: Vec<u64> = Vec::new();
        let bridgelines = parse_into_bridgelines(working_resources);
        for bridge in bridgelines {
            /* TODO: Functionality for marking bridges as unreachable/blocked should eventually happen here.
                        It is currently not enabled as there is not yet a reliable way to determine that a bridge is blocked.
                        This means that migrations to unblocked bridges do not currently work but can be easily enabled by parsing the
                        list of `blocked resources` from rdsys or another source with something like the following:
                        let res = context.add_unreachable(bridgeline);
                        if res {
                            println!(
                                "BridgeLine {:?} successfully marked unreachable: {:?}",
                                bridgeline
                            );
                        } else {
                            println!(
                                "BridgeLine {:?} NOT marked unreachable, saved for next update!",
                                bridge.uid_fingerprint
                            );
                        }
            */
            let res = self.update_bridge(bridge);
            if res {
                println!(
                    "BridgeLine {:?} successfully updated.",
                    bridge.uid_fingerprint
                );
                accounted_for_bridges.push(bridge.uid_fingerprint);
                self.metrics.existing_or_updated_bridges.inc();
                // Assume non-failing bridges that are not found in the bridge table are new bridges and save them for later
            } else {
                println!("BridgeLine: {:?} not found in Lox's Bridgetable. Save it as a new resource for now!", bridge.uid_fingerprint);
                self.append_extra_bridges(bridge);
                self.metrics.new_bridges.inc();
            }
        }
        accounted_for_bridges
    }

    pub fn handle_not_working_resources(
        &self,
        not_working_resources: Vec<Resource>,
        mut accounted_for_bridges: Vec<u64>,
    ) -> Vec<u64> {
        let (grace_period, failing) = sort_for_parsing(not_working_resources);
        // Update bridges in the bridge table that are failing but within the grace period
        for bridge in grace_period {
            let res = self.update_bridge(bridge);
            if res {
                println!(
                    "BridgeLine {:?} successfully updated.",
                    bridge.uid_fingerprint
                );
                accounted_for_bridges.push(bridge.uid_fingerprint);
                self.metrics.existing_or_updated_bridges.inc();
            }
        }
        // Next, handle the failing bridges. If resource last passed tests >=ACCEPTED_HOURS_OF_FAILURE ago,
        // it should be replaced with a working resource and be removed from the bridgetable.
        for bridge in failing {
            let res = self.replace_with_new(bridge);
            if res == lox_library::ReplaceSuccess::Replaced {
                println!(
                    "BridgeLine {:?} successfully replaced.",
                    bridge.uid_fingerprint
                );
                accounted_for_bridges.push(bridge.uid_fingerprint);
                self.metrics.removed_bridges.inc();
            } else if res == lox_library::ReplaceSuccess::NotReplaced {
                // Add the bridge to the list of to_be_replaced bridges in the Lox context and try
                // again to replace at the next update (nothing changes in the Lox Authority)
                println!(
                    "BridgeLine {:?} NOT replaced, saved for next update!",
                    bridge.uid_fingerprint
                );
                self.new_to_be_replaced_bridge(bridge);
                self.metrics.existing_or_updated_bridges.inc();
                accounted_for_bridges.push(bridge.uid_fingerprint);
            } else {
                // NotFound
                assert!(
                    res == lox_library::ReplaceSuccess::NotFound,
                    "ReplaceSuccess incorrectly set"
                );
                println!(
                    "BridgeLine {:?} no longer in bridge table.",
                    bridge.uid_fingerprint
                );
            }
        }
        accounted_for_bridges
    }

    // Sync resources received from rdsys with the Lox bridgetable
    pub fn sync_with_bridgetable(&self, resources: ResourceState) {
        // Check if each resource is already in the Lox bridgetable. If it is, it's probably fine
        // to replace the existing resource with the incoming one to account for changes
        // save a list of accounted for bridges and deal with the unaccounted for bridges at the end
        let mut accounted_for_bridges: Vec<u64> = Vec::new();
        // ensure all working resources are updated and accounted for
        if let Some(working_resources) = resources.working {
            accounted_for_bridges = self.handle_working_resources(working_resources);
        }
        if let Some(not_working_resources) = resources.not_working {
            accounted_for_bridges =
                self.handle_not_working_resources(not_working_resources, accounted_for_bridges);
        }
        let mut ba_clone = self.ba.lock().unwrap();
        let total_reachable = ba_clone.bridge_table.reachable.len();
        match total_reachable.cmp(&accounted_for_bridges.len()) {
            Ordering::Greater => {
                let unaccounted_for = ba_clone.find_and_remove_unaccounted_for_bridges(accounted_for_bridges);
                for bridgeline in unaccounted_for {
                    match self.replace_with_new(bridgeline) {
                        lox_library::ReplaceSuccess::Replaced => {
                            println!("BridgeLine {:?} not found in rdsys update was successfully replaced.", bridgeline.uid_fingerprint);
                            self.metrics.removed_bridges.inc();
                        }
                        lox_library::ReplaceSuccess::NotReplaced => {
                            // Add the bridge to the list of to_be_replaced bridges in the Lox context and try
                            // again to replace at the next update (nothing changes in the Lox Authority)
                            println!("BridgeLine {:?} not found in rdsys update NOT replaced, saved for next update!",
                            bridgeline.uid_fingerprint);
                            self.new_to_be_replaced_bridge(bridgeline);
                            self.metrics.existing_or_updated_bridges.inc();
                        }
                        lox_library::ReplaceSuccess::NotFound => println!(
                            "BridgeLine {:?} no longer in reachable bridges.",
                            bridgeline.uid_fingerprint
                        ),
                    }
                }
            }
            Ordering::Less => println!("Something unexpected occurred: The number of reachable bridges should not be less than those updated from rdsys"),
            _ => (),

        }
        // Finally, assign any extra_bridges to new buckets if there are enough
        while self.extra_bridges.lock().unwrap().len() >= MAX_BRIDGES_PER_BUCKET {
            let bucket = self.remove_extra_bridges();
            // TODO: Decide the circumstances under which a bridge is allocated to an open_inv or spare bucket,
            // eventually also do some more fancy grouping of new resources, i.e., by type or region
            let mut db_obj = self.db.lock().unwrap();
            match ba_clone.add_spare_bucket(bucket, &mut db_obj) {
                Ok(_) => (),
                Err(e) => {
                    println!("Error: {:?}", e);
                    for bridge in bucket {
                        self.append_extra_bridges(bridge);
                    }
                }
            }
        }
    }

    pub fn append_extra_bridges(&self, bridge: BridgeLine) {
        let mut extra_bridges = self.extra_bridges.lock().unwrap();
        extra_bridges.push(bridge);
    }

    pub fn remove_extra_bridges(&self) -> [BridgeLine; MAX_BRIDGES_PER_BUCKET] {
        let mut extra_bridges = self.extra_bridges.lock().unwrap();
        let mut return_bridges = [BridgeLine::default(); MAX_BRIDGES_PER_BUCKET];
        for bridge in return_bridges.iter_mut() {
            if let Some(extra) = extra_bridges.pop() {
                *bridge = extra
            }
        }
        return_bridges
    }

    pub fn remove_single_bridge(&self) {
        let mut extra_bridges = self.extra_bridges.lock().unwrap();
        let length = extra_bridges.len();
        _ = extra_bridges.remove(length - 1)
    }

    pub fn new_to_be_replaced_bridge(&self, bridge: BridgeLine) {
        let mut to_be_replaced_bridges = self.to_be_replaced_bridges.lock().unwrap();
        to_be_replaced_bridges.push(bridge);
    }

    pub fn allocate_leftover_bridges(&self) {
        let mut ba_obj = self.ba.lock().unwrap();
        let mut db_obj = self.db.lock().unwrap();
        let mut extra_bridges = self.extra_bridges.lock().unwrap();
        ba_obj.allocate_bridges(&mut extra_bridges, &mut db_obj);
    }

    pub fn add_openinv_bucket(&self, bucket: [BridgeLine; 3]) {
        let mut ba_obj = self.ba.lock().unwrap();
        let mut db_obj = self.db.lock().unwrap();
        match ba_obj.add_openinv_bridges(bucket, &mut db_obj) {
            Ok(_) => (),
            Err(e) => {
                println!("Error: {:?}", e);
                for bridge in bucket {
                    self.append_extra_bridges(bridge);
                }
            }
        }
    }

    pub fn add_spare_bucket(&self, bucket: [BridgeLine; 3]) {
        let mut ba_obj = self.ba.lock().unwrap();
        let mut db_obj = self.db.lock().unwrap();
        match ba_obj.add_spare_bucket(bucket, &mut db_obj) {
            Ok(_) => (),
            Err(e) => {
                println!("Error: {:?}", e);
                for bridge in bucket {
                    self.append_extra_bridges(bridge);
                }
            }
        }
    }

    // Attempt to remove a bridge that is failing tests and replace it with a bridge from the
    // available bridges or from a spare bucket
    pub fn replace_with_new(&self, bridgeline: BridgeLine) -> lox_library::ReplaceSuccess {
        let mut ba_obj = self.ba.lock().unwrap();
        let eb_obj = self.extra_bridges.lock().unwrap();
        let available_bridge = eb_obj.last();
        let result = ba_obj.bridge_replace(&bridgeline, available_bridge);
        // .last() doesn't actually remove the object so we still have to do that if the bridge was
        // replaced with an available bridge
        if result == lox_library::ReplaceSuccess::Replaced && eb_obj.len() > 0 {
            self.remove_single_bridge();
        }
        result
    }

    /* TODO: Uncomment when bridge blocking is finalized
        pub fn add_unreachable(&self, bridgeline: BridgeLine) -> bool {
            let mut ba_obj = self.ba.lock().unwrap();
            let mut db_obj = self.db.lock().unwrap();
            ba_obj.bridge_unreachable(&bridgeline, &mut db_obj)
        }
    */

    pub fn update_bridge(&self, bridgeline: BridgeLine) -> bool {
        let mut ba_obj = self.ba.lock().unwrap();
        ba_obj.bridge_update(&bridgeline)
    }

    #[cfg(test)]
    /// For testing only: manually advance the day by the given number
    /// of days.
    pub fn advance_days_test(&self, num: u16) {
        let mut ba_obj = self.ba.lock().unwrap();
        ba_obj.advance_days(num); // FOR TESTING ONLY
        println!("Today's date according to server: {}", ba_obj.today());
    }

    pub fn encrypt_table(&self) -> HashMap<u32, EncryptedBucket> {
        let mut ba_obj = self.ba.lock().unwrap();
        ba_obj.enc_bridge_table().clone()
    }

    fn pubkeys(&self) -> Vec<IssuerPubKey> {
        let ba_obj = self.ba.lock().unwrap();
        // vector of public keys (to serialize)
        vec![
            ba_obj.lox_pub.clone(),
            ba_obj.migration_pub.clone(),
            ba_obj.migrationkey_pub.clone(),
            ba_obj.reachability_pub.clone(),
            ba_obj.invitation_pub.clone(),
        ]
    }

    fn gen_invite(&self) -> Result<lox_utils::Invite, ExceededMaxBridgesError> {
        let mut obj = self.db.lock().unwrap();
        match obj.invite() {
            Ok(invite) => {
                if obj.current_k == 1 {
                    self.metrics.k_reset_count.inc();
                }
                // Count the number of total bridge requests
                if obj.daily_bridges_distributed <= MAX_DAILY_BRIDGES {
                    self.metrics.buckets_requested_today.inc();
                }
                Ok(lox_utils::Invite { invite })
            }
            Err(e) => Err(e),
        }
    }

    fn open_inv(&self, req: open_invite::Request) -> Result<open_invite::Response, ProofError> {
        let mut ba_obj = self.ba.lock().unwrap();
        ba_obj.handle_open_invite(req)
    }

    fn trust_promo(
        &self,
        req: trust_promotion::Request,
    ) -> Result<trust_promotion::Response, ProofError> {
        let mut ba_obj = self.ba.lock().unwrap();
        ba_obj.handle_trust_promotion(req)
    }

    fn trust_migration(&self, req: migration::Request) -> Result<migration::Response, ProofError> {
        let mut ba_obj = self.ba.lock().unwrap();
        ba_obj.handle_migration(req)
    }

    fn level_up(&self, req: level_up::Request) -> Result<level_up::Response, ProofError> {
        let mut ba_obj = self.ba.lock().unwrap();
        ba_obj.handle_level_up(req)
    }

    fn issue_invite(
        &self,
        req: issue_invite::Request,
    ) -> Result<issue_invite::Response, ProofError> {
        let mut ba_obj = self.ba.lock().unwrap();
        ba_obj.handle_issue_invite(req)
    }

    fn redeem_invite(
        &self,
        req: redeem_invite::Request,
    ) -> Result<redeem_invite::Response, ProofError> {
        let mut ba_obj = self.ba.lock().unwrap();
        ba_obj.handle_redeem_invite(req)
    }

    fn check_blockage(
        &self,
        req: check_blockage::Request,
    ) -> Result<check_blockage::Response, ProofError> {
        let mut ba_obj = self.ba.lock().unwrap();
        ba_obj.handle_check_blockage(req)
    }

    fn blockage_migration(
        &self,
        req: blockage_migration::Request,
    ) -> Result<blockage_migration::Response, ProofError> {
        let mut ba_obj = self.ba.lock().unwrap();
        ba_obj.handle_blockage_migration(req)
    }

    // Generate and return an open invitation token
    pub fn generate_invite(self) -> Response<Body> {
        let invite = self.gen_invite();
        match invite {
            Ok(invite) => match serde_json::to_string(&invite) {
                Ok(resp) => prepare_header(resp),
                Err(e) => {
                    println!("Error parsing Invite to JSON");
                    prepare_error_header(e.to_string())
                }
            },
            Err(e) => {
                println!("Error parsing Invite to JSON");
                prepare_error_header(e.to_string())
            }
        }
    }

    // Return the serialized encrypted bridge table
    pub fn send_reachability_cred(self) -> Response<Body> {
        let enc_table = self.encrypt_table();
        let etable = lox_utils::EncBridgeTable { etable: enc_table };
        match serde_json::to_string(&etable) {
            Ok(resp) => prepare_header(resp),
            Err(e) => {
                println!("Error parsing encrypted bridgetable to JSON");
                prepare_error_header(e.to_string())
            }
        }
    }

    // Return the serialized pubkeys for the Bridge Authority
    pub fn send_keys(self) -> Response<Body> {
        let pubkeys = self.pubkeys();
        match serde_json::to_string(&pubkeys) {
            Ok(resp) => prepare_header(resp),
            Err(e) => {
                println!("Error parsing Pubkeys to JSON");
                prepare_error_header(e.to_string())
            }
        }
    }

    pub fn verify_and_send_open_cred(self, request: Bytes) -> Response<Body> {
        let req = match serde_json::from_slice(&request) {
            Ok(req) => req,
            Err(e) => return prepare_error_header(e.to_string()),
        };
        match self.open_inv(req) {
            Ok(resp) => {
                let response = serde_json::to_string(&resp).unwrap();
                self.metrics.open_inv_count.inc();
                prepare_header(response)
            }
            Err(e) => {
                println!("Invalid Open Invitation request, Proof Error");
                prepare_error_header(e.to_string())
            }
        }
    }

    pub fn verify_and_send_trust_promo(self, request: Bytes) -> Response<Body> {
        let req: trust_promotion::Request = match serde_json::from_slice(&request) {
            Ok(req) => req,
            Err(e) => return prepare_error_header(e.to_string()),
        };
        match self.trust_promo(req) {
            Ok(resp) => {
                let response = serde_json::to_string(&resp).unwrap();
                self.metrics.trust_promo_count.inc();
                prepare_header(response)
            }
            Err(e) => {
                println!("Invalid Trust Promotion request, Proof Error");
                prepare_error_header(e.to_string())
            }
        }
    }

    pub fn verify_and_send_trust_migration(self, request: Bytes) -> Response<Body> {
        let req: migration::Request = match serde_json::from_slice(&request) {
            Ok(req) => req,
            Err(e) => return prepare_error_header(e.to_string()),
        };
        match self.trust_migration(req) {
            Ok(resp) => {
                let response = serde_json::to_string(&resp).unwrap();
                self.metrics.trust_mig_count.inc();
                prepare_header(response)
            }
            Err(e) => {
                println!("Invalid Trust Migration request, Proof Error");
                prepare_error_header(e.to_string())
            }
        }
    }

    pub fn verify_and_send_level_up(self, request: Bytes) -> Response<Body> {
        let req: level_up::Request = match serde_json::from_slice(&request) {
            Ok(req) => req,
            Err(e) => return prepare_error_header(e.to_string()),
        };
        match self.level_up(req) {
            Ok(resp) => {
                let response = serde_json::to_string(&resp).unwrap();
                self.metrics.level_up_count.inc();
                prepare_header(response)
            }
            Err(e) => {
                println!("Invalid Level up request, Proof Error");
                prepare_error_header(e.to_string())
            }
        }
    }

    pub fn verify_and_send_issue_invite(self, request: Bytes) -> Response<Body> {
        let req: issue_invite::Request = match serde_json::from_slice(&request) {
            Ok(req) => req,
            Err(e) => return prepare_error_header(e.to_string()),
        };
        match self.issue_invite(req) {
            Ok(resp) => {
                let response = serde_json::to_string(&resp).unwrap();
                self.metrics.issue_invite_count.inc();
                prepare_header(response)
            }
            Err(e) => {
                println!("Invalid Issue invite request, Proof Error");
                prepare_error_header(e.to_string())
            }
        }
    }

    pub fn verify_and_send_redeem_invite(self, request: Bytes) -> Response<Body> {
        let req: redeem_invite::Request = match serde_json::from_slice(&request) {
            Ok(req) => req,
            Err(e) => return prepare_error_header(e.to_string()),
        };
        match self.redeem_invite(req) {
            Ok(resp) => {
                let response = serde_json::to_string(&resp).unwrap();
                self.metrics.redeem_invite_count.inc();
                prepare_header(response)
            }
            Err(e) => {
                println!("Invalid Redeem Invite request, Proof Error");
                prepare_error_header(e.to_string())
            }
        }
    }

    pub fn verify_and_send_check_blockage(self, request: Bytes) -> Response<Body> {
        let req: check_blockage::Request = match serde_json::from_slice(&request) {
            Ok(req) => req,
            Err(e) => return prepare_error_header(e.to_string()),
        };
        match self.check_blockage(req) {
            Ok(resp) => {
                let response = serde_json::to_string(&resp).unwrap();
                self.metrics.check_blockage_count.inc();
                prepare_header(response)
            }
            Err(e) => {
                println!("Invalid Check blockage request, Proof Error");
                prepare_error_header(e.to_string())
            }
        }
    }

    pub fn verify_and_send_blockage_migration(self, request: Bytes) -> Response<Body> {
        let req: blockage_migration::Request = match serde_json::from_slice(&request) {
            Ok(req) => req,
            Err(e) => return prepare_error_header(e.to_string()),
        };
        match self.blockage_migration(req) {
            Ok(resp) => {
                let response = serde_json::to_string(&resp).unwrap();
                self.metrics.blockage_migration_count.inc();
                prepare_header(response)
            }
            Err(e) => {
                println!("Invalid Blockage Migration request, Proof Error");
                prepare_error_header(e.to_string())
            }
        }
    }
}

fn prepare_header(response: String) -> Response<Body> {
    let mut resp = Response::new(Body::from(response));
    resp.headers_mut()
        .insert("Access-Control-Allow-Origin", HeaderValue::from_static("*"));
    resp
}

fn prepare_error_header(error: String) -> Response<Body> {
    Response::builder()
        .status(hyper::StatusCode::BAD_REQUEST)
        .body(Body::from(error))
        .unwrap()
}