const std = @import("std");
const expect = std.testing.expect;
const expectEql = std.testing.expectEqual;
const expectStrEql = std.testing.expectEqualStrings;

const flecs = @import("../src/main.zig");
const c = flecs.c;

const context = flecs.Context(void);
const Entity = context.Entity;
const Iter = context.Iter;
const Id = context.Id;

pub const MAX_SYS_COLUMNS = 20;
pub const MAX_ENTITIES = 256;
pub const MAX_INVOCATIONS = 1024;

pub const Probe = struct {
    system: c.ecs_entity_t,
    event: c.ecs_entity_t,
    eventId: c.ecs_id_t,
    offset: i32,
    count: i32,
    invoked: i32,
    termCount: i32,
    termIndex: i32,
    e: [MAX_ENTITIES]c.ecs_entity_t,
    c: [MAX_SYS_COLUMNS][MAX_INVOCATIONS]c.ecs_entity_t,
    s: [MAX_SYS_COLUMNS][MAX_INVOCATIONS]c.ecs_entity_t,
    param: ?*anyopaque,

    pub fn init() Probe {
        return std.mem.zeroes(Probe);
    }

    pub fn probeSystemWithContext(ctx: *Probe, it: *Iter) !void {
        ctx.*.param = it.*.param;
        ctx.*.system = it.*.system;
        ctx.*.event = it.*.event;
        ctx.*.eventId = it.*.eventId;
        ctx.*.offset = 0;
        ctx.*.termCount = it.*.fieldCount;
        ctx.*.termIndex = it.*.termIndex;

        for (0..ctx.*.term_count) |i| {
            ctx.*.c[ctx.*.invoked][i] = it.*.ids[i];
            ctx.*.s[ctx.*.invoked][i] = it.fieldSource(i + 1);

            const e = it.fieldId(i + 1);
            try expect(e != 0);
        }

        for (0..it.*.count) |i| {
            if (i + ctx.*.count < 256) {
                ctx.*.e[i + ctx.*.count] = it.*.entities[i];
            } else {
                // Can't store more than that, tests shouldn't
                // rely on getting back more than 256 results.
                unreachable;
            }
        }
        ctx.*.count += it.*.count;

        ctx.*.invoked += 1;
    }

    pub fn probeIter(it: *Iter) !void {
        var ctx = c.ecs_get_context(it.*.world);
        if (ctx == null) ctx = it.*.ctx;
        if (ctx) |ct| {
            var p: *Probe = @ptrCast(ct);
            p.probeSystemWithContext(it);
        }
    }
};