// Items generated the graphql schema trigger this lint, so just disable for this entire file
#![allow(clippy::pub_enum_variant_names)]

use graphql_client::{GraphQLQuery, Response};
use reqwest::Client;
use serde::{de::DeserializeOwned, Serialize};
use std::{collections::BTreeMap, fmt};
use tracing::{error, info, warn};
use uuid::Uuid;

#[derive(GraphQLQuery)]
#[graphql(
    schema_path = "buildkite/schema.json",
    query_path = "buildkite/org.gql",
    response_derives = "Debug"
)]
struct OrgId;

#[derive(GraphQLQuery)]
#[graphql(
    schema_path = "buildkite/schema.json",
    query_path = "buildkite/org.gql",
    response_derives = "Debug"
)]
struct OrgAccess;

#[derive(GraphQLQuery)]
#[graphql(
    schema_path = "buildkite/schema.json",
    query_path = "buildkite/jobs.gql",
    response_derives = "Debug"
)]
struct GetPipelineById;

#[derive(GraphQLQuery)]
#[graphql(
    schema_path = "buildkite/schema.json",
    query_path = "buildkite/jobs.gql",
    response_derives = "Debug"
)]
struct GetBuilds;

#[derive(GraphQLQuery)]
#[graphql(
    schema_path = "buildkite/schema.json",
    query_path = "buildkite/jobs.gql",
    response_derives = "Debug"
)]
struct GetRunningBuilds;

#[derive(Debug)]
pub enum BkErr {
    InvalidHttpHeader(http::header::InvalidHeaderValue),
    Http(reqwest::Error),
    Reqwest(reqwest::Error),
    Json(serde_json::error::Error),
    UnknownOrg(String),
    InvalidOrgId(String),
    UnknownPipeline(String),
    Threadpool(std::io::Error),
    Request(GraphQLErrors),
    InvalidResponse(String),
}

impl std::error::Error for BkErr {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match self {
            Self::InvalidHttpHeader(ihv) => Some(ihv),
            Self::Http(h) => Some(h),
            Self::Reqwest(r) => Some(r),
            Self::Json(j) => Some(j),
            Self::Threadpool(tp) => Some(tp),
            _ => None,
        }
    }
}

impl fmt::Display for BkErr {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::InvalidHttpHeader(ihv) => write!(f, "invalid header value: {}", ihv),
            Self::Http(re) => write!(f, "http error: {}", re),
            Self::Reqwest(re) => write!(f, "http request error: {}", re),
            Self::Json(je) => write!(f, "json error: {}", je),
            Self::UnknownOrg(o) => write!(f, "unknown org '{}'", o),
            Self::InvalidOrgId(o) => write!(f, "invalid org id '{}'", o),
            Self::UnknownPipeline(p) => write!(f, "unknown pipeline '{}'", p),
            Self::Threadpool(io) => write!(f, "threadpool error: {}", io),
            Self::Request(api) => write!(f, "API failure: {}", api),
            Self::InvalidResponse(res) => write!(f, "invalid response {}", res),
        }
    }
}

impl From<reqwest::Error> for BkErr {
    fn from(e: reqwest::Error) -> Self {
        Self::Reqwest(e)
    }
}

#[derive(Debug)]
pub struct GraphQLErrors {
    errors: Vec<graphql_client::Error>,
}

impl fmt::Display for GraphQLErrors {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_list().entries(self.errors.iter()).finish()
    }
}

async fn send_request<
    'a,
    Req: Serialize,
    Res: DeserializeOwned + std::marker::Unpin + std::fmt::Debug,
>(
    client: &'a Client,
    req: &'a Req,
    hash: Option<u64>,
) -> Result<(Option<Res>, Option<u64>), BkErr> {
    use std::hash::Hasher;

    let res = client.post(crate::BK_API_URL).json(req).send().await?;

    let res = res.error_for_status().map_err(BkErr::Http)?;

    let content_type = res.headers().get(http::header::CONTENT_TYPE);
    if content_type
        != Some(&http::header::HeaderValue::from_static(
            "application/json; charset=utf-8",
        ))
    {
        return Err(BkErr::InvalidResponse(format!(
            "invalid content-type: {:?}",
            content_type
        )));
    }

    let json_body = res.bytes().await?;

    let new_hash = {
        let mut hasher = twox_hash::XxHash::default();
        hasher.write(&json_body);
        Some(hasher.finish())
    };

    if hash.is_some() && new_hash == hash {
        return Ok((None, new_hash));
    }

    let res: Response<Res> = serde_json::from_slice(&json_body).map_err(|e| {
        error!(
            "json error for response: {:?}",
            String::from_utf8(json_body.to_vec())
        );
        BkErr::Json(e)
    })?;

    if let Some(errs) = res.errors {
        return Err(BkErr::Request(GraphQLErrors { errors: errs }));
    }

    Ok((res.data, new_hash))
}

macro_rules! parse_uuid {
    ($uuid_str:expr) => {
        match Uuid::parse_str($uuid_str) {
            Ok(u) => u,
            Err(err) => {
                error!("failed to parse Buildkite UUID '{}': {}", $uuid_str, err);
                return None;
            }
        };
    };
}

#[derive(Debug, PartialEq)]
pub enum BuildStates {
    /// The build was skipped
    Skipped,
    /// The build has yet to start running jobs
    Scheduled,
    /// The build is currently running jobs
    Running,
    /// The build passed
    Passed,
    /// The build failed
    Failed,
    /// The build is currently being canceled
    Canceling,
    /// The build was canceled
    Canceled,
    /// The build is blocked
    Blocked,
    /// The build wasn't run
    NotRun,
    /// Unknown build state
    Unknown,
}

impl From<get_builds::BuildStates> for BuildStates {
    fn from(bs: get_builds::BuildStates) -> Self {
        use get_builds::BuildStates as BS;

        match bs {
            BS::SKIPPED => BuildStates::Skipped,
            BS::SCHEDULED => BuildStates::Scheduled,
            BS::RUNNING => BuildStates::Running,
            BS::PASSED => BuildStates::Passed,
            BS::FAILED => BuildStates::Failed,
            BS::CANCELING => BuildStates::Canceling,
            BS::CANCELED => BuildStates::Canceled,
            BS::BLOCKED => BuildStates::Blocked,
            BS::NOT_RUN => BuildStates::NotRun,
            BS::Other(_) => BuildStates::Unknown,
        }
    }
}

#[derive(Debug, PartialEq)]
pub enum JobStates {
    /// The job has just been created and doesn't have a state yet
    Pending,
    /// The job is waiting on a `wait` step to finish
    Waiting,
    /// The job was in a `Waiting` state when the build failed
    WaitingFailed,
    /// The job is waiting on a `block` step to finish
    Blocked,
    /// The job was in a `Blocked` state when the build failed
    BlockedFailed,
    /// This `block` job has been manually unblocked
    Unblocked,
    /// This `block` job was in a `Blocked` state when the build failed
    UnblockedFailed,
    /// The job is waiting for jobs with the same concurrency group to finish
    Limited,
    /// The job is scheduled and waiting for an agent
    Scheduled,
    /// The job has been assigned to an agent, and it's waiting for it to accept
    Assigned,
    /// The job was accepted by the agent, and now it's waiting to start running
    Accepted,
    /// The job is runing
    Running,
    /// The job has finished
    Finished,
    /// The job is currently canceling
    Canceling,
    /// The job was canceled
    Canceled,
    /// The job is timing out for taking too long
    TimingOut,
    /// The job timed out
    TimedOut,
    /// The job was skipped
    Skipped,
    /// The jobs configuration means that it can't be run
    Broken,
    /// An unknown job state
    Unknown,
}

impl From<get_builds::JobStates> for JobStates {
    fn from(js: get_builds::JobStates) -> Self {
        use get_builds::JobStates as JS;

        match js {
            JS::PENDING => JobStates::Pending,
            JS::WAITING => JobStates::Waiting,
            JS::WAITING_FAILED => JobStates::WaitingFailed,
            JS::BLOCKED => JobStates::Blocked,
            JS::BLOCKED_FAILED => JobStates::BlockedFailed,
            JS::UNBLOCKED => JobStates::Unblocked,
            JS::UNBLOCKED_FAILED => JobStates::UnblockedFailed,
            JS::LIMITED => JobStates::Limited,
            JS::SCHEDULED => JobStates::Scheduled,
            JS::ASSIGNED => JobStates::Assigned,
            JS::ACCEPTED => JobStates::Accepted,
            JS::RUNNING => JobStates::Running,
            JS::FINISHED => JobStates::Finished,
            JS::CANCELING => JobStates::Canceling,
            JS::CANCELED => JobStates::Canceled,
            JS::TIMING_OUT => JobStates::TimingOut,
            JS::TIMED_OUT => JobStates::TimedOut,
            JS::SKIPPED => JobStates::Skipped,
            JS::BROKEN => JobStates::Broken,
            JS::Other(_) => JobStates::Unknown,
        }
    }
}

#[derive(Debug)]
pub struct Job {
    /// Unique identifier for the job
    pub uuid: Uuid,
    /// The job's friendly identifier
    pub label: String,
    /// The containing build's UUID
    pub build_uuid: Uuid,
    /// The exit code for the job, if it has finished execution
    pub exit_status: Option<i32>,
    /// The current state of the job
    pub state: JobStates,
    /// The agent query rules used to determine which agents
    /// can pick this job up
    query_rules: String,
    /// The name of the agent the job was assigned to
    pub agent: Option<String>,
}

fn iter_query_rules(query_rules: &str) -> impl Iterator<Item = (&str, Option<&str>)> {
    query_rules.split(',').filter_map(|rule| {
        let mut i = rule.splitn(2, '=');

        match (i.next(), i.next()) {
            (Some(k), Some(v)) => {
                if v.is_empty() || v == "*" {
                    Some((k, None))
                } else {
                    Some((k, Some(v)))
                }
            }
            _ => None,
        }
    })
}

impl Job {
    pub fn iter_query_rules(&self) -> impl Iterator<Item = (&str, Option<&str>)> {
        iter_query_rules(&self.query_rules)
    }
}

#[derive(Debug)]
pub struct Build {
    /// Unique identifier for the build
    pub uuid: Uuid,
    /// Metadata attached to the build
    pub metadata: BTreeMap<String, String>,
    /// The commit message that triggered the build
    pub message: Option<String>,
    /// The commit identifier the build pertains to
    pub commit: String,
    /// The current state of the build
    pub state: BuildStates,
    /// The list of currently known jobs in the build
    pub jobs: Vec<Job>,
}

impl std::cmp::PartialOrd for Build {
    fn partial_cmp(&self, other: &Build) -> Option<std::cmp::Ordering> {
        Some(self.uuid.cmp(&other.uuid))
    }
}

impl std::cmp::Ord for Build {
    fn cmp(&self, other: &Build) -> std::cmp::Ordering {
        self.uuid.cmp(&other.uuid)
    }
}

impl std::cmp::PartialEq for Build {
    fn eq(&self, other: &Build) -> bool {
        self.uuid == other.uuid
    }
}

impl std::cmp::Eq for Build {}

//#[derive(Clone)]
pub struct Builds {
    pub builds: Vec<Build>,
    pub pipeline: String,
}

// Monitors Buildkite's GraphQL API for events of interest
pub struct Monitor {
    client: Client,
}

#[derive(Clone)]
struct KnownBuild {
    uuid: Uuid,
    commit: String,
}

impl std::cmp::PartialOrd for KnownBuild {
    fn partial_cmp(&self, other: &KnownBuild) -> Option<std::cmp::Ordering> {
        Some(self.uuid.cmp(&other.uuid))
    }
}

impl std::cmp::Ord for KnownBuild {
    fn cmp(&self, other: &KnownBuild) -> std::cmp::Ordering {
        self.uuid.cmp(&other.uuid)
    }
}

impl std::cmp::PartialEq for KnownBuild {
    fn eq(&self, other: &KnownBuild) -> bool {
        self.uuid == other.uuid
    }
}

impl std::cmp::Eq for KnownBuild {}

impl Monitor {
    pub async fn with_token(token: String) -> Result<Monitor, BkErr> {
        use http::{header::AUTHORIZATION, HeaderMap};
        let mut headers = HeaderMap::new();

        // Every Buildkite request requires auth so just make it a default
        headers.insert(
            AUTHORIZATION,
            format!("Bearer {}", token)
                .parse::<http::header::HeaderValue>()
                .map_err(BkErr::InvalidHttpHeader)?,
        );

        let client = reqwest::ClientBuilder::new()
            .default_headers(headers)
            .build()?;

        Ok(Self { client })
    }

    #[inline]
    pub fn client(&self) -> Client {
        self.client.clone()
    }

    pub async fn watch<'a>(
        &'a self,
        pipeline_identifier: &'a str,
    ) -> Result<futures::channel::mpsc::Receiver<Builds>, BkErr> {
        let req_body = GetPipelineById::build_query(get_pipeline_by_id::Variables {
            id: pipeline_identifier.to_owned(),
        });

        let (res_body, _) =
            send_request::<_, get_pipeline_by_id::ResponseData>(&self.client, &req_body, None)
                .await?;

        let pipeline = res_body
            .and_then(|root| root.node.map(|rn| rn.on))
            .and_then(|n| {
                if let get_pipeline_by_id::GetPipelineByIdNodeOn::Pipeline(pipeline) = n {
                    Some(pipeline)
                } else {
                    None
                }
            })
            .ok_or_else(|| BkErr::UnknownPipeline(pipeline_identifier.to_owned()))?;

        let get_pipeline_by_id::GetPipelineByIdNodeOnPipeline {
            name: pipeline_name,
            id: pipeline_id,
            description: pipeline_description,
            ..
        } = pipeline;

        let (mut tx, rx) = futures::channel::mpsc::channel(100);

        let client = self.client.clone();

        let poll = async move {
            info!(
                "watching pipeline {}({}) '{}'",
                pipeline_name,
                pipeline_id,
                pipeline_description.as_deref().unwrap_or("<none>")
            );

            // Currently we just poll aggressively, a better option would be to add
            // a webhook for the `job.scheduled` event that invokes a cloud function, which
            // then posts a cloud pubsub message that we listen to instead as it should
            // be much lower cost for everyone involved, at the expense of additional
            // complexity
            let mut failure_count = 0u32;
            let mut query_hash = None;
            let mut known_builds = Vec::new();

            let mut sleep = 1;

            loop {
                tokio::time::sleep(std::time::Duration::from_secs(sleep)).await;

                let builds =
                    match get_builds(&client, &pipeline_id, &mut known_builds, &mut query_hash)
                        .await
                    {
                        Ok(builds) => {
                            if failure_count > 0 {
                                info!("successfully sent query after {} failures", failure_count);
                                failure_count = 0;
                                sleep = 1;
                            }

                            match builds {
                                Some(builds) => Builds {
                                    builds,
                                    pipeline: pipeline_name.clone(),
                                },
                                None => continue,
                            }
                        }
                        Err(err) => {
                            failure_count += 1;
                            sleep *= 2;

                            // cap at 60 seconds
                            sleep = std::cmp::min(sleep, 60);

                            warn!(
                                "failed to send query {} time(s) in a row: {}",
                                failure_count, err
                            );
                            continue;
                        }
                    };

                // Try to send to our channel, if it fails it means the receiver
                // was dropped and we can stop polling
                if tx.try_send(builds).is_err() {
                    break;
                }
            }

            info!(
                "stopped watching pipeline {}({})",
                pipeline_name, pipeline_id,
            );
        };

        tokio::spawn(poll);

        Ok(rx)
    }
}

async fn get_builds(
    client: &Client,
    pipeline_id: &str,
    known_builds: &mut Vec<KnownBuild>,
    query_hash: &mut Option<u64>,
) -> Result<Option<Vec<Build>>, BkErr> {
    let req_body = GetRunningBuilds::build_query(get_running_builds::Variables {
        id: pipeline_id.to_owned(),
    });

    let (res_body, _hash) =
        send_request::<_, get_running_builds::ResponseData>(client, &req_body, None).await?;

    let builds_to_check = res_body
        .and_then(|root| root.node)
        .and_then(|node| match node.on {
            get_running_builds::GetRunningBuildsNodeOn::Pipeline(pipeline) => pipeline.builds,
            _ => None,
        })
        .and_then(|in_builds| in_builds.edges)
        .map(|builds| {
            builds
                .into_iter()
                .filter_map(|n| n.and_then(|n| n.node))
                .filter_map(|build| {
                    Some(KnownBuild {
                        uuid: parse_uuid!(&build.uuid),
                        commit: build.commit,
                    })
                })
                .collect::<Vec<_>>()
        });

    let commits: Vec<_> = known_builds
        .iter()
        .map(|kb| kb.commit.clone())
        .chain(
            builds_to_check
                .unwrap_or_default()
                .into_iter()
                .map(|kb| kb.commit),
        )
        .collect();

    let req_body = GetBuilds::build_query(get_builds::Variables {
        id: pipeline_id.to_owned(),
        commits: Some(commits),
    });

    let (res_body, hash) =
        send_request::<_, get_builds::ResponseData>(client, &req_body, *query_hash).await?;

    // Don't bother sending an update to jobifier if the Buildkite state hasn't changed
    if *query_hash == hash {
        return Ok(None);
    }

    *query_hash = hash;

    let builds = res_body
        .and_then(|root| {
            if let Some(node) = root.node {
                match node.on {
                    get_builds::GetBuildsNodeOn::Pipeline(pipeline) => pipeline.builds,
                    _ => None,
                }
            } else {
                None
            }
        })
        .and_then(|in_builds| in_builds.edges)
        .and_then(|builds| {
            let mut builds: Vec<_> = builds
                .into_iter()
                .filter_map(|n| n.and_then(|n| n.node))
                .filter_map(|build| {
                    let uuid = parse_uuid!(&build.uuid);

                    let jobs: Option<Vec<_>> = build.jobs.and_then(|jn| jn.edges)
                        .map(|jobs| {
                            jobs.into_iter()
                                .filter_map(|e| e.and_then(|n| n.node))
                                .filter_map(|job| {
                                    match job {
                                        get_builds::GetBuildsNodeOnPipelineBuildsEdgesNodeJobsEdgesNode::JobTypeCommand(cmd) => {
                                            Some(Job {
                                                uuid: parse_uuid!(&cmd.uuid),
                                                build_uuid: uuid,
                                                label: cmd.label.unwrap_or_else(|| "<unlabeled>".to_owned()),
                                                state: cmd.state.into(),
                                                query_rules: cmd.agent_query_rules.as_ref().map(|v| v.join(",")).unwrap_or_default(),
                                                exit_status: cmd.exit_status.and_then(|es| es.parse::<i32>().ok()),
                                                agent: cmd.agent.and_then(|a| a.name),
                                            })
                                        }
                                        _ => None
                                    }
                                }).collect()
                        });

                    let jobs = match jobs {
                        Some(ref j) if j.is_empty() => return None,
                        None => return None,
                        Some(j) => j,
                    };

                    // Fill out the metadata for the build, if we've been triggered by another build
                    // add its metadata first and then override them if they're also set on this build
                    let metadata = {
                        let mut meta = BTreeMap::new();

                        if let Some(md) = build.triggered_from.and_then(|tf| tf.build.and_then(|b| b.meta_data.and_then(|md| md.edges))) {
                            meta.extend(md.into_iter().filter_map(|e| {
                                e.and_then(|e| e.node.map(|kv| (kv.key, kv.value)))
                            }));
                        }

                        if let Some(md) = build.meta_data.and_then(|md| md.edges) {
                            meta.extend(md.into_iter().filter_map(|e| {
                                e.and_then(|e| e.node.map(|kv| (kv.key, kv.value)))
                            }));
                        }

                        meta
                    };

                    Some(Build {
                        jobs,
                        metadata,
                        message: build.message,
                        commit: build.commit,
                        uuid,
                        state: build.state.into(),
                    })
                })
                .collect();

            builds.sort();

            if !builds.is_empty() {
                Some(builds)
            } else {
                None
            }
        });

    known_builds.clear();

    if let Some(ref builds) = builds {
        known_builds.extend(builds.iter().filter_map(|b| match b.state {
            BuildStates::Running => Some(KnownBuild {
                uuid: b.uuid,
                commit: b.commit.clone(),
            }),
            _ => None,
        }))
    }

    Ok(builds)
}

#[cfg(test)]
mod test {
    #[test]
    fn iters_agent_rules() {
        let mut iter = super::iter_query_rules("queue=something,os=linux,blah=thing");

        assert_eq!(iter.next(), Some(("queue", Some("something"))));
        assert_eq!(iter.next(), Some(("os", Some("linux"))));
        assert_eq!(iter.next(), Some(("blah", Some("thing"))));
        assert_eq!(iter.next(), None);
    }

    #[test]
    fn iters_empty_agent_rules() {
        let mut iter = super::iter_query_rules("");
        assert_eq!(iter.next(), None);
    }
}