# frozen_string_literal: true

module FeatherCaseWizard
  class PackageBuilder
    attr_reader :config, :root, :toolchain, :model_source, :renderer_source

    def initialize(config, root: CASES_ROOT, toolchain: Toolchain.new,
                   model_source: MODEL_SOURCE, renderer_source: RENDERER_SOURCE,
                   reporter: nil)
      @config = config
      @root = Pathname(root)
      @toolchain = toolchain
      @model_source = Pathname(model_source)
      @renderer_source = Pathname(renderer_source)
      @reporter = reporter || ->(_message) {}
    end

    def build!
      toolchain.check!
      verify_sources!
      config.validate!
      config.generator["sha256"] = Digest::SHA256.file(model_source).hexdigest
      config.generator["created_with"] ||= "feather-case-wizard"

      FileUtils.mkdir_p(root)
      destination = config.package_dir(root)
      stage = Pathname(Dir.mktmpdir(".#{config.slug}-stage-", root.to_s))
      prepare_package(stage, destination)
      install_atomically(stage, destination)
      destination
    ensure
      FileUtils.rm_rf(stage) if stage&.exist?
    end

    private

    def verify_sources!
      raise ToolError, "Missing model source: #{model_source}" unless model_source.file?
      raise ToolError, "Missing preview renderer: #{renderer_source}" unless renderer_source.file?
    end

    def prepare_package(stage, previous)
      source_dir = stage.join("source")
      FileUtils.mkdir_p(source_dir)
      FileUtils.cp(model_source, source_dir.join("feather_case.scad"))
      FileUtils.cp(renderer_source, source_dir.join("render_stl_previews.py"))
      FileUtils.cp(ROOT.join("templates/standalone_build.rb"), stage.join("build.rb"))

      copy_history(previous, stage)
      write_configuration(stage)
      generate_exports(stage)
      generate_previews(stage)
      write_summary(stage)
    end

    def copy_history(previous, stage)
      history = stage.join("history")
      if previous.directory?
        old_history = previous.join("history")
        FileUtils.cp_r(old_history, history) if old_history.directory?
        FileUtils.mkdir_p(history)
        stamp = Time.now.utc.strftime("%Y%m%dT%H%M%S.%6NZ")
        FileUtils.cp(previous.join("case.yml"), history.join("case-#{stamp}.yml")) if
          previous.join("case.yml").file?
        old_source = previous.join("source/feather_case.scad")
        if old_source.file? &&
           Digest::SHA256.file(old_source).hexdigest != config.generator["sha256"]
          FileUtils.cp(old_source, history.join("feather_case-#{stamp}.scad"))
        end
      end
    end

    def write_configuration(stage)
      File.write(stage.join("case.yml"), config.to_yaml)
      values = config.parameters.to_h do |key, value|
        [key, openscad_literal(value)]
      end
      customizer = {
        "parameterSets" => {config.slug => values},
        "fileFormatVersion" => "1"
      }
      File.write(stage.join("parameters.json"), JSON.pretty_generate(customizer) + "\n")
      FileUtils.chmod(0o755, stage.join("build.rb"))
    end

    def generate_exports(stage)
      config.outputs["formats"].each do |format|
        directory = stage.join("exports", format)
        FileUtils.mkdir_p(directory)
        config.printable_parts.each do |part|
          report("Exporting #{part}.#{format}")
          export_model(stage, directory.join("#{part}.#{format}"), part)
        end
      end
    end

    def generate_previews(stage)
      previews = stage.join("previews")
      scratch = stage.join(".preview-meshes")
      FileUtils.mkdir_p([previews, scratch])
      assembly_stl = scratch.join("assembly.stl")
      report("Preparing assembly preview")
      export_model(stage, assembly_stl, "assembly",
                   "exploded_view" => config.outputs["assembly_exploded_view"],
                   "show_references" => false)
      render(stage, assembly_stl, previews, "assembly")

      config.printable_parts.each do |part|
        report("Rendering #{part} preview")
        mesh = scratch.join("#{part}.stl")
        export_model(stage, mesh, part) unless mesh.file?
        render(stage, mesh, previews, part, ["iso"])
      end
      FileUtils.rm_rf(scratch)
    end

    def export_model(stage, output, part, overrides = {})
      model = stage.join("source/feather_case.scad")
      parameters = config.model_parameters.merge(overrides).merge("part" => part)
      command = [toolchain.openscad, "-o", output.to_s]
      parameters.each do |name, value|
        command.concat(["-D", "#{name}=#{openscad_literal(value)}"])
      end
      command << model.to_s
      toolchain.run!(*command)
      raise ToolError, "OpenSCAD did not create #{output}" unless output.file? && output.size.positive?
    end

    def render(stage, mesh, output_dir, basename, views = nil)
      renderer = stage.join("source/render_stl_previews.py")
      command = [
        toolchain.blender, "--background", "-noaudio", "--python", renderer.to_s, "--",
        mesh.to_s, output_dir.to_s, basename
      ]
      command << views.join(",") if views
      toolchain.run!(*command, env: {"DISPLAY" => nil, "WAYLAND_DISPLAY" => nil})
    end

    def write_summary(stage)
      dims = config.dimensions
      parts = config.printable_parts.map { |part| "`#{part}`" }.join(", ")
      text = <<~MARKDOWN
        # #{config.name}

        Generated by the Feather Case Wizard.

        - Top profile: `#{config.parameters["top_profile"]}`
        - FeatherWings: #{config.parameters["wing_count"]}
        - Battery compartment: #{config.parameters["battery_enabled"] ? "yes" : "no"}
        - 1/4-20 insert: #{config.parameters["tripod_insert_enabled"] ? "yes" : "no"}
        - Approximate exterior: #{format("%.1f", dims["length"])} × #{format("%.1f", dims["width"])} × #{format("%.1f", dims["height"] + config.parameters["lid_thickness"])} mm
        - Formats: #{config.outputs["formats"].join(", ")}
        - Parts: #{parts}
        - Custom cutouts: #{config.cutouts.length}

        Run `ruby build.rb` in this directory to regenerate exports and previews.
        OpenSCAD and Blender must be installed. Set `OPENSCAD` or `BLENDER` to
        override their executable paths.

        To open the saved Customizer values manually:

        ```bash
        openscad -p parameters.json -P #{config.slug} source/feather_case.scad
        ```

        The 3MF files contain portable geometry only. Choose printer, filament,
        plate, and slicing settings in Bambu Studio.
      MARKDOWN
      File.write(stage.join("README.md"), text)
    end

    def install_atomically(stage, destination)
      old = root.join(".#{config.slug}-old-#{Process.pid}")
      if destination.exist?
        FileUtils.mv(destination, old)
      end
      FileUtils.mv(stage, destination)
      FileUtils.rm_rf(old) if old.exist?
    rescue StandardError
      FileUtils.mv(old, destination) if old&.exist? && !destination.exist?
      raise
    end

    def openscad_literal(value)
      case value
      when String then JSON.generate(value)
      when TrueClass then "true"
      when FalseClass then "false"
      when Numeric then value.to_s
      when Array then "[#{value.map { |item| openscad_literal(item) }.join(",")}]"
      else
        raise ConfigError, "Cannot convert #{value.inspect} to OpenSCAD"
      end
    end

    def report(message)
      @reporter.call(message)
    end
  end
end