import Elementary
import ElementaryHTMX
import Routes
import Styleguide

struct HeatingBalancePointForm: HTML, Sendable {
  let mode: HeatingBalancePoint.Mode
  let heatLossMode: HeatingBalancePoint.HeatLoss.Mode
  let response: HeatingBalancePoint.Response?

  init(
    mode: HeatingBalancePoint.Mode?,
    heatLossMode: HeatingBalancePoint.HeatLoss.Mode? = nil,
    response: HeatingBalancePoint.Response? = nil
  ) {
    self.mode = mode ?? .thermal
    self.heatLossMode = heatLossMode ?? .estimated
    self.response = response
  }

  var content: some HTML {
    FormHeader(label: "Balance Point - \(mode.label)", svg: .scale)
    // TODO: Toggle button

    form(
      .hx.post(route: .heatingBalancePoint(.index)),
      .hx.target("#result")
    ) {
      div(.class("space-y-6")) {
        switch mode {
        case .thermal:
          ThermalFields(heatLossMode: heatLossMode)
        case .economic:
          div {}
        }

        div {
          SubmitButton(label: "Calculate Balance Point")
        }
      }
    }

    div(.id("result")) {
      if let response {
        HeatingBalancePointResponse(response: response)
      }
    }
  }

  struct ThermalFields: HTML, Sendable {
    let heatLossMode: HeatingBalancePoint.HeatLoss.Mode

    var content: some HTML {
      LabeledContent(label: "System Size (Tons)") {
        Input(id: "systemSize", placeholder: "System size")
          .attributes(.type(.number), .min("1"), .step("0.5"), .autofocus, .required)
      }
      div {
        div(.class("mb-4")) {
          h4(.class("text-lg font-bold")) { "Capacities" }
          p(.class("text-sm")) {
            "Entering known capacities gives better results, otherwise capacities will be estimated."
          }
        }
        div(.class("grid grid-cols-1 lg:grid-cols-2 gap-4")) {
          LabeledContent(label: "Capacity @ 47° (BTU/h)") {
            Input(id: "capacityAt47", placeholder: "Capacity @ 47° (optional)")
              .attributes(.type(.number), .min("1"), .step("0.5"))
          }
          LabeledContent(label: "Capacity @ 17° (BTU/h)") {
            Input(id: "capacityAt17", placeholder: "Capacity @ 17° (optional)")
              .attributes(.type(.number), .min("1"), .step("0.5"))
          }
        }
      }
      HeatLossFields(mode: heatLossMode)
    }
  }

  struct HeatLossFields: HTML, Sendable {
    let mode: HeatingBalancePoint.HeatLoss.Mode

    var content: some HTML {
      div(.id("heatLossFields")) {
        div(.class("flex flex-wrap justify-between")) {
          h4(.class("text-lg font-bold")) { "Heat Loss - \(mode.label)" }
          Toggle(
            isOn: mode == .estimated,
            onLabel: HeatingBalancePoint.HeatLoss.Mode.estimated.label,
            onAttributes: [
              .hx.get(route: .heatingBalancePoint(.heatLossFields(mode: .estimated))),
              .hx.target("#heatLossFields")
            ],
            offLabel: HeatingBalancePoint.HeatLoss.Mode.known.label,
            offAttributes: [
              .hx.get(route: .heatingBalancePoint(.heatLossFields(mode: .known))),
              .hx.target("#heatLossFields")
            ]
          )
          .attributes(.class("mb-6"))
        }
        switch mode {
        case .known:
          knownFields
        case .estimated:
          simplifiedFields
        }
      }
    }

    private var simplifiedFields: some HTML {
      LabeledContent(label: "Building Size (ft²)") {
        Input(id: "simplifiedHeatLoss", placeholder: "Square feet")
          .attributes(.type(.number), .min("1"), .step("0.5"), .required)
      }
    }

    private var knownFields: some HTML {
      LabeledContent(label: "Heat Loss (BTU/h)") {
        Input(id: "knownHeatLoss", placeholder: "Heat loss")
          .attributes(.type(.number), .min("1"), .step("0.5"), .required)
      }
    }

  }

}

struct HeatingBalancePointResponse: HTML, Sendable {

  let response: HeatingBalancePoint.Response

}

private extension HeatingBalancePoint.Mode {

  var label: String { rawValue.capitalized }

}

private extension HeatingBalancePoint.HeatLoss.Mode {
  var label: String { rawValue.capitalized }
}