const std = @import("std");
const Coverage = @import("build/Coverage.zig");

pub fn build(b: *std.Build) void {
    const target = b.standardTargetOptions(.{});
    const optimize = b.standardOptimizeOption(.{});

    // -- Engine module (the calculation library) --
    const engine_mod = b.addModule("engine", .{
        .root_source_file = b.path("engine/src/engine.zig"),
        .target = target,
        .optimize = optimize,
    });

    // -- Vaxis dependency (TUI library) --
    const vaxis_dep = b.dependency("vaxis", .{
        .target = target,
        .optimize = optimize,
    });

    // -- Engine static library (for linking into the main binary) --
    const engine_lib = b.addLibrary(.{
        .linkage = .static,
        .name = "tally-engine",
        .root_module = engine_mod,
    });
    b.installArtifact(engine_lib);

    // -- Engine shared library (for Android JNI) --
    const engine_shared = b.addLibrary(.{
        .linkage = .dynamic,
        .name = "tally",
        .root_module = b.createModule(.{
            .root_source_file = b.path("engine/src/c_api.zig"),
            .target = target,
            .optimize = optimize,
            .imports = &.{
                .{ .name = "engine", .module = engine_mod },
            },
        }),
    });
    b.installArtifact(engine_shared);

    // -- Main binary (CLI + TUI in one) --
    const exe = b.addExecutable(.{
        .name = "tally",
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/main.zig"),
            .target = target,
            .optimize = optimize,
            .imports = &.{
                .{ .name = "engine", .module = engine_mod },
                .{ .name = "vaxis", .module = vaxis_dep.module("vaxis") },
            },
        }),
    });
    b.installArtifact(exe);

    // -- Tests --
    const engine_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("engine/src/engine.zig"),
            .target = target,
            .optimize = optimize,
        }),
    });

    const cli_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/main.zig"),
            .target = target,
            .optimize = optimize,
            .imports = &.{
                .{ .name = "engine", .module = engine_mod },
                .{ .name = "vaxis", .module = vaxis_dep.module("vaxis") },
            },
        }),
    });

    const run_engine_tests = b.addRunArtifact(engine_tests);
    const run_cli_tests = b.addRunArtifact(cli_tests);

    // TUI tests need their own root: src/main.zig only reaches tui.zig from
    // main(), which is never analyzed in test mode, so its tests would be
    // silently skipped if we relied on the CLI test target.
    const tui_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/tui.zig"),
            .target = target,
            .optimize = optimize,
            .imports = &.{
                .{ .name = "engine", .module = engine_mod },
                .{ .name = "vaxis", .module = vaxis_dep.module("vaxis") },
            },
        }),
    });
    const run_tui_tests = b.addRunArtifact(tui_tests);

    const test_step = b.step("test", "Run unit tests");
    test_step.dependOn(&run_engine_tests.step);
    test_step.dependOn(&run_cli_tests.step);
    test_step.dependOn(&run_tui_tests.step);

    // -- Coverage step (uses kcov, Linux x86_64/aarch64 only) --
    //
    // One report per source tree, with disjoint include patterns so no file is
    // accounted for twice. The CLI test binary also compiles tui.zig (main.zig
    // imports it) but never runs its tests, so the CLI report is narrowed to
    // main.zig and src/cli; without that narrowing the TUI would appear
    // near-uncovered in one report and covered in another.
    {
        var cov = Coverage.init(b);

        const engine_cov = b.createModule(.{
            .root_source_file = b.path("engine/src/engine.zig"),
            .target = target,
            .optimize = optimize,
        });
        _ = cov.addModule(engine_cov, "tally-engine", &.{"engine/src"});

        const cli_cov = b.createModule(.{
            .root_source_file = b.path("src/main.zig"),
            .target = target,
            .optimize = optimize,
            .imports = &.{
                .{ .name = "engine", .module = engine_mod },
                .{ .name = "vaxis", .module = vaxis_dep.module("vaxis") },
            },
        });
        _ = cov.addModule(cli_cov, "tally-cli", &.{ "src/main.zig", "src/cli" });

        const tui_cov = b.createModule(.{
            .root_source_file = b.path("src/tui.zig"),
            .target = target,
            .optimize = optimize,
            .imports = &.{
                .{ .name = "engine", .module = engine_mod },
                .{ .name = "vaxis", .module = vaxis_dep.module("vaxis") },
            },
        });
        // tui.zig plus its views. main.zig and src/cli are deliberately excluded
        // even though they are not compiled into this binary, so the two app reports
        // stay disjoint by construction rather than by accident.
        _ = cov.addModule(tui_cov, "tally-tui", &.{ "src/tui.zig", "src/tui" });
    }

    // -- Run step --
    const run_step = b.step("run", "Run tally");
    const run_cmd = b.addRunArtifact(exe);
    run_step.dependOn(&run_cmd.step);
    run_cmd.step.dependOn(b.getInstallStep());
    if (b.args) |args| {
        run_cmd.addArgs(args);
    }
}