// --- LIBS ---
const std = @import("std");
const System = @import("system.zig");
const Context = @import("context.zig");
const TypeID = @import("../template/type_id.zig").of;
const Self = @This();

//
// FIELDS
//

data: std.ArrayList(System),
alloc: std.mem.Allocator,

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn init(alloc: std.mem.Allocator) Self {
    return .{
        .data = .empty,
        .alloc = alloc,
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn deinit(self: *Self) void {
    self.data.deinit(self.alloc);
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn add(
    self: *Self,
    comptime T: type,
    execute: *const fn (Context) anyerror!void,
) !void {
    // --- GET ID ---
    const stage_id = TypeID(T);

    // --- NEW SYSTEM ---
    try self.data.append(self.alloc, .{
        .stage_id = stage_id,
        .execute = execute,
    });
    errdefer _ = self.data.swapRemove(self.data.items.len - 1);
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn addMany(
    self: *Self,
    comptime T: type,
    values: []const *const fn (Context) anyerror!void,
) !void {
    for (values) |exe| {
        try self.add(T, exe);
    }
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn addBefore(
    self: *Self,
    comptime Stage: type,
    comptime Before: type,
    execute: *const fn (Context) anyerror!void,
) !void {
    const stage_id = TypeID(Stage);
    const insert_idx = self.firstStageIndex(TypeID(Before));

    try self.data.insert(self.alloc, insert_idx, .{
        .stage_id = stage_id,
        .execute = execute,
    });
    errdefer _ = self.data.swapRemove(insert_idx);
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn addManyBefore(
    self: *Self,
    comptime Stage: type,
    comptime Before: type,
    values: []const *const fn (Context) anyerror!void,
) !void {
    const stage_id = TypeID(Stage);
    var insert_idx = self.firstStageIndex(TypeID(Before));

    for (values) |exe| {
        try self.data.insert(self.alloc, insert_idx, .{
            .stage_id = stage_id,
            .execute = exe,
        });
        insert_idx += 1;
    }
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn addAfter(
    self: *Self,
    comptime Stage: type,
    comptime After: type,
    execute: *const fn (Context) anyerror!void,
) !void {
    const stage_id = TypeID(Stage);
    const insert_idx = self.lastStageIndex(TypeID(After));

    try self.data.insert(self.alloc, insert_idx, .{
        .stage_id = stage_id,
        .execute = execute,
    });
    errdefer _ = self.data.swapRemove(insert_idx);
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn addManyAfter(
    self: *Self,
    comptime Stage: type,
    comptime After: type,
    values: []const *const fn (Context) anyerror!void,
) !void {
    const stage_id = TypeID(Stage);
    var insert_idx = self.lastStageIndex(TypeID(After));

    for (values) |exe| {
        try self.data.insert(self.alloc, insert_idx, .{
            .stage_id = stage_id,
            .execute = exe,
        });
        insert_idx += 1;
    }
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn runAll(
    self: *Self,
    ctx: Context,
) !void {
    for (self.data.items) |sys| {
        try sys.execute(ctx);
    }
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn run(
    self: *Self,
    comptime T: type,
    ctx: Context,
) !void {
    // --- GET ID ---
    const stage_id = TypeID(T);

    // --- RUN ---
    for (self.data.items) |sys| {
        if (sys.stage_id != stage_id) continue;
        try sys.execute(ctx);
    }
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn runMany(
    self: *Self,
    comptime Ts: []const type,
    ctx: Context,
) !void {
    inline for (Ts) |T| {
        try self.run(T, ctx);
    }
}

/// ----------------------------------------------------
/// ----------------------------------------------------
fn firstStageIndex(self: *Self, stage_id: u64) usize {
    for (self.data.items, 0..) |sys, i| {
        if (sys.stage_id == stage_id) return i;
    }
    return self.data.items.len;
}

/// ----------------------------------------------------
/// ----------------------------------------------------
fn lastStageIndex(self: *Self, stage_id: u64) usize {
    var last: usize = self.data.items.len;
    for (self.data.items, 0..) |sys, i| {
        if (sys.stage_id == stage_id) last = i + 1;
    }
    return last;
}