use std::{cmp::Ordering, collections::HashSet, fmt::Display};

use serde::{Deserialize, Serialize};
use sled::IVec;

use crate::jira::Issue;

#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
pub struct MergeRequestRef {
    pub url: String,
    pub state: String,
}

#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
pub struct Task {
    pub jira_key: String,
    pub description: String,
    pub merge_requests: Vec<MergeRequestRef>,
    pub jira_priority: i64,
    pub local_priority: i64,
    pub status: String,
    pub tags: HashSet<String>,
}

const STATUS_PRIORITY: [&str; 4] = ["Blocked", "InProgress", "DevReady", "Backlog"];

impl PartialOrd for Task {
    /// We sort tasks first by their status. If those are equal, we sort by their priority, favoring the `local_priority`.
    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for Task {
    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
        if self.eq(other) {
            return Ordering::Equal;
        }

        {
            let a = STATUS_PRIORITY.iter().position(|s| **s == self.status);
            let b = STATUS_PRIORITY.iter().position(|s| **s == other.status);
            let o = a.cmp(&b);
            if o != Ordering::Equal {
                return o;
            }
        }

        {
            let o = self.local_priority.cmp(&other.local_priority);
            if o != Ordering::Equal {
                return o;
            }
        }

        self.jira_priority.cmp(&other.jira_priority)
    }
}

impl Display for Task {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let Self {
            description,
            jira_key,
            merge_requests,
            jira_priority,
            local_priority,
            status,
            tags,
        } = self;
        let tags_text = tags
            .iter()
            .map(String::as_str)
            .collect::<Vec<&str>>()
            .join(", ");
        let mr_text = if merge_requests.len() > 0 {
            format!(" {} MRs", merge_requests.len())
        } else {
            "".into()
        };
        f.write_fmt(format_args!(
            "{jira_key} {status:>10} {jira_priority} {description} [{tags_text}]{mr_text}",
        ))
    }
}

impl TryFrom<IVec> for Task {
    type Error = anyhow::Error;

    fn try_from(value: IVec) -> std::prelude::v1::Result<Self, Self::Error> {
        serde_json::from_slice(&value).map_err(|e| e.into())
    }
}

impl TryInto<IVec> for &Task {
    type Error = anyhow::Error;

    fn try_into(self) -> std::prelude::v1::Result<IVec, Self::Error> {
        Ok(IVec::from(serde_json::to_vec(self)?))
    }
}

impl TryFrom<&Issue> for Task {
    type Error = anyhow::Error;

    fn try_from(value: &Issue) -> std::prelude::v1::Result<Self, Self::Error> {
        let mut tags = HashSet::from_iter(value.fields.labels.iter().map(|s| s.to_owned()));
        if let Some(cs) = &value.fields.components {
            for c in cs.iter().map(|c| c.name.to_owned()) {
                tags.insert(c);
            }
        }
        Ok(Self {
            jira_key: value.key.to_owned(),
            description: value.fields.summary.to_owned(),
            merge_requests: vec![],
            jira_priority: value.fields.priority.id.parse()?,
            local_priority: value.fields.priority.id.parse()?,
            status: value.fields.status.name.to_owned(),
            tags,
        })
    }
}