//! Milestone domain types and DTOs.

use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use strum_macros::EnumString;
use crate::id_types::{MilestoneId, UserId, ProjectId};
use super::shared::{CssClass, DbValue, ParseableEnum};

// ============ Milestones ============

/// Lifecycle status of a milestone.
// `ascii_case_insensitive` so the lowercase `db_value()` form ("open"/"completed")
// round-trips back through `from_str_or_default`; without it a stored "completed"
// failed to parse and silently reverted to `Open` on every read.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Default, EnumString)]
#[strum(ascii_case_insensitive)]
pub enum MilestoneStatus {
    /// Milestone is still being worked toward.
    #[strum(serialize = "Open")]
    #[default]
    Open,
    /// All milestone tasks are done.
    #[strum(serialize = "Completed")]
    Completed,
}

impl MilestoneStatus {
    /// Returns a human-readable display string.
    pub fn as_str(&self) -> &'static str {
        match self {
            MilestoneStatus::Open => "Open",
            MilestoneStatus::Completed => "Completed",
        }
    }

}

impl ParseableEnum for MilestoneStatus {}

impl DbValue for MilestoneStatus {
    fn db_value(&self) -> &'static str {
        match self {
            MilestoneStatus::Open => "open",
            MilestoneStatus::Completed => "completed",
        }
    }
}

impl CssClass for MilestoneStatus {
    fn css_class(&self) -> &'static str {
        match self {
            MilestoneStatus::Open => "milestone-open",
            MilestoneStatus::Completed => "milestone-completed",
        }
    }
}

/// A project milestone representing a scope boundary.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct Milestone {
    /// Unique identifier.
    pub id: MilestoneId,
    /// Owner user ID.
    pub user_id: UserId,
    /// Parent project ID.
    pub project_id: ProjectId,
    /// Milestone name.
    pub name: String,
    /// Optional description.
    pub description: String,
    /// Display order (lower = first).
    pub position: i32,
    /// Target completion date.
    pub target_date: Option<chrono::NaiveDate>,
    /// Current status.
    pub status: MilestoneStatus,
    /// When the milestone was created.
    pub created_at: DateTime<Utc>,
}

/// Data for creating a new milestone.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct NewMilestone {
    pub project_id: ProjectId,
    pub name: String,
    pub description: String,
    pub position: i32,
    pub target_date: Option<chrono::NaiveDate>,
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn milestone_status_db_value_round_trips() {
        // Regression: the lowercase db_value form must parse back to the same
        // variant (was reverting Completed -> Open on read).
        for status in [MilestoneStatus::Open, MilestoneStatus::Completed] {
            let stored = status.db_value();
            assert_eq!(MilestoneStatus::from_str_or_default(stored), status);
        }
        // The capitalized display form still parses too.
        assert_eq!(
            MilestoneStatus::from_str_or_default("Completed"),
            MilestoneStatus::Completed
        );
    }
}