//! Sync protocol objects (SPEC §14.4.2, §14.4.3, §14.4.6).

use serde::{Deserialize, Serialize};
use utoipa::ToSchema;
use uuid::Uuid;

use super::account::Account;
use super::audit::{AuditEntry, EntityType};
use super::category::Category;
use super::expense::{Expense, Split, SplitMode};
use super::recurring::RecurringTemplate;
use super::settlement::{Allocation, Settlement};
use super::user::User;
use super::{DateSchema, OreSchema, ServerVersionSchema, TimestampSchema, UuidSchema};

/// E-31 `GET /sync` response: one page; every array present (possibly empty) and sorted by `server_version`.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub struct SyncPullResponse {
    /// `meta.sync_epoch`, 32 lowercase hex characters.
    #[schema(pattern = "^[0-9a-f]{32}$")]
    pub epoch: String,
    pub since: i64,
    /// The highest `server_version` in the page, or `since` when the page is empty.
    pub next_since: i64,
    pub has_more: bool,
    #[schema(value_type = TimestampSchema)]
    pub server_time: String,
    pub users: Vec<User>,
    pub categories: Vec<Category>,
    pub accounts: Vec<Account>,
    pub recurring_templates: Vec<RecurringTemplate>,
    pub expenses: Vec<Expense>,
    pub settlements: Vec<Settlement>,
    pub audit_entries: Vec<AuditEntry>,
}

/// Exactly the client-writable fields of an expense (SPEC §14.4.3); server-owned fields are ignored if sent. A
/// delete is the full entity with `deleted_at` set.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub struct PushedExpense {
    #[schema(value_type = UuidSchema)]
    pub id: Uuid,
    #[schema(value_type = UuidSchema)]
    pub account_id: Uuid,
    #[schema(value_type = UuidSchema)]
    pub category_id: Uuid,
    #[schema(value_type = OreSchema)]
    pub amount_ore: i64,
    pub description: String,
    pub notes: String,
    #[schema(value_type = DateSchema)]
    pub expense_date: String,
    #[schema(value_type = UuidSchema)]
    pub payer_user_id: Uuid,
    pub split_mode: SplitMode,
    pub splits: Vec<Split>,
    #[schema(value_type = TimestampSchema)]
    pub created_at: String,
    #[schema(value_type = TimestampSchema)]
    pub updated_at: String,
    #[serde(deserialize_with = "super::required_nullable")]
    #[schema(value_type = Option<TimestampSchema>, required = true)]
    pub deleted_at: Option<String>,
}

/// Exactly the client-writable fields of a settlement (SPEC §14.4.3).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub struct PushedSettlement {
    #[schema(value_type = UuidSchema)]
    pub id: Uuid,
    #[schema(value_type = UuidSchema)]
    pub from_user_id: Uuid,
    #[schema(value_type = UuidSchema)]
    pub to_user_id: Uuid,
    #[schema(value_type = OreSchema)]
    pub amount_ore: i64,
    #[schema(value_type = DateSchema)]
    pub settlement_date: String,
    pub note: String,
    pub allocations: Vec<Allocation>,
    #[schema(value_type = TimestampSchema)]
    pub created_at: String,
    #[schema(value_type = TimestampSchema)]
    pub updated_at: String,
    #[serde(deserialize_with = "super::required_nullable")]
    #[schema(value_type = Option<TimestampSchema>, required = true)]
    pub deleted_at: Option<String>,
}

/// The constant `"expense"` (the discriminator value of [`ExpenseMutation`]).
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub enum ExpenseTag {
    #[serde(rename = "expense")]
    Expense,
}

/// The constant `"settlement"` (the discriminator value of [`SettlementMutation`]).
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub enum SettlementTag {
    #[serde(rename = "settlement")]
    Settlement,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub struct ExpenseMutation {
    #[schema(value_type = UuidSchema)]
    pub mutation_id: Uuid,
    #[schema(inline)]
    pub entity_type: ExpenseTag,
    pub entity: PushedExpense,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub struct SettlementMutation {
    #[schema(value_type = UuidSchema)]
    pub mutation_id: Uuid,
    #[schema(inline)]
    pub entity_type: SettlementTag,
    pub entity: PushedSettlement,
}

/// One pushed change, discriminated by `entity_type`.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
#[serde(untagged)]
#[schema(discriminator(property_name = "entity_type", mapping(
    ("expense" = "#/components/schemas/ExpenseMutation"),
    ("settlement" = "#/components/schemas/SettlementMutation"),
)))]
pub enum Mutation {
    Expense(ExpenseMutation),
    Settlement(SettlementMutation),
}

/// E-32 `POST /sync` request: 1 to 100 mutations (more is 422 `batch_too_large`).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub struct SyncPushRequest {
    pub mutations: Vec<Mutation>,
}

/// A full wire object of the type named by `entity_type`.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
#[serde(untagged)]
pub enum SyncEntity {
    Expense(Expense),
    Settlement(Settlement),
}

/// The constant `"accepted"`.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub enum AcceptedTag {
    #[serde(rename = "accepted")]
    Accepted,
}

/// The constant `"rejected"`.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub enum RejectedTag {
    #[serde(rename = "rejected")]
    Rejected,
}

/// Exhaustive (SPEC §14.4.6).
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
#[serde(rename_all = "snake_case")]
pub enum RejectionReason {
    Stale,
    Deleted,
    ValidationFailed,
    ReferenceNotFound,
    ClockSkew,
}

/// An accepted mutation. Accepted and rejected results have different key sets (SPEC §14.4.3).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub struct AcceptedResult {
    #[schema(value_type = UuidSchema)]
    pub mutation_id: Uuid,
    pub entity_type: EntityType,
    #[schema(value_type = UuidSchema)]
    pub entity_id: Uuid,
    #[schema(inline)]
    pub status: AcceptedTag,
    #[schema(value_type = ServerVersionSchema)]
    pub server_version: i64,
    // The full wire object after processing. (A doc comment here would make utoipa wrap the schema in `allOf`.)
    #[schema(inline)]
    pub entity: SyncEntity,
}

/// A rejected mutation (SPEC §14.4.6).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub struct RejectedResult {
    #[schema(value_type = UuidSchema)]
    pub mutation_id: Uuid,
    pub entity_type: EntityType,
    #[schema(value_type = UuidSchema)]
    pub entity_id: Uuid,
    #[schema(inline)]
    pub status: RejectedTag,
    pub reason: RejectionReason,
    /// For validation failures, the domain error token of SPEC §14.5.3.
    pub message: String,
    // The stored row, or null when the server has no row with that id.
    #[schema(inline, required = true)]
    pub current: Option<SyncEntity>,
}

/// One result per mutation, discriminated by `status`.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
#[serde(untagged)]
#[schema(discriminator(property_name = "status", mapping(
    ("accepted" = "#/components/schemas/AcceptedResult"),
    ("rejected" = "#/components/schemas/RejectedResult"),
)))]
pub enum MutationResult {
    Accepted(AcceptedResult),
    Rejected(RejectedResult),
}

/// E-32 response: one result per mutation, in request order.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, ToSchema)]
pub struct SyncPushResponse {
    #[schema(value_type = TimestampSchema)]
    pub server_time: String,
    pub results: Vec<MutationResult>,
}