# Copyright (c) 2018 Kelvin Say
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

library(FinCal)

source('utility_functions.R')

# ---------------------------------------------------------------------------------------------------------------------------
#
# ---------------------------------------------------------------------------------------------------------------------------
process_Financial_Viability <- function(technical_summary, finance_info, tariff_info, costs_info, timing = FALSE, runIRR = FALSE) {
  if (timing) {
    start_time <- now()
    time_a <- start_time
  }

  inputs <- list('Finance' = finance_info,
                 'Tariff' = tariff_info,
                 'Costs' = costs_info,
                 'Technical' = technical_summary$Inputs)

  analysis_years <- finance_info$'Analysis Years'
  pv_count <- length(technical_summary$'PV Capacity (Wp)')
  battery_count <- length(technical_summary$'Battery Capacity (Wh)')

  # Costs: PV, Battery, System
  # --------------------------
  v_pv_cost <- technical_summary$'PV Capacity (Wp)' / 1000 * costs_info$'PV Cost ($/kWp)'
  v_battery_cost <- technical_summary$'Battery Capacity (Wh)' / 1000 * costs_info$'Battery Cost ($/kWh)'

  temp_A <- matrix(v_pv_cost, nrow=pv_count, ncol=battery_count)
  temp_B <- matrix(v_battery_cost, nrow=pv_count, ncol=battery_count, byrow = TRUE)
  mat_system_cost <- temp_A + temp_B

  # Savings: PV, Battery, System
  # ----------------------------
  v_mask <- rep(1, pv_count)
  for (i in 1:pv_count) {
    if (technical_summary$'PV Capacity (Wp)'[i] > tariff_info$'FiT System Limit (Wp)') {
      v_mask[i] <- 0
    }
  }
  mat_pv_savings_import <- crossfill_2D_3D_matrix(technical_summary$Yearly$'Directly Used (kWh)', battery_count)
  mat_pv_savings_export <- crossfill_2D_3D_matrix(v_mask * (technical_summary$Yearly$'Generated (kWh)' - technical_summary$Yearly$'Directly Used (kWh)'), battery_count)
  mat_pv_savings <- round(mat_pv_savings_import * tariff_info$'Import ($/kWh)' + mat_pv_savings_export * tariff_info$'Export ($/kWh)', 2)

  mat_battery_savings_import <- technical_summary$Yearly$'Battery Discharged (kWh)'

 mat_battery_savings_export <- v_mask * (technical_summary$Yearly$'Exported (kWh)' - crossfill_2D_3D_matrix(technical_summary$Yearly$'Generated (kWh)' - technical_summary$Yearly$'Directly Used (kWh)', battery_count))
  mat_battery_savings <- round(mat_battery_savings_import * tariff_info$'Import ($/kWh)' + mat_battery_savings_export * tariff_info$'Export ($/kWh)', 2)

  mat_system_savings_import <- mat_pv_savings_import + mat_battery_savings_import
  mat_system_savings_export <- mat_pv_savings_export + mat_battery_savings_export
  mat_system_savings <- round(mat_system_savings_import *  tariff_info$'Import ($/kWh)' + mat_system_savings_export * tariff_info$'Export ($/kWh)', 2)

  if (timing) {
    print(paste("--> Savings calculated:", round(now() - time_a,2), "seconds"))
    time_a <- now()
  }

  # Cash flow calculation (analysis_years): PV, Battery, System
  # -----------------------------------------------------------
  mat_pv_cf <- array(0, dim=c(pv_count, battery_count, analysis_years+1))
  for (i in 1:pv_count) {
    capital_cost <- v_pv_cost[i]
    for (j in 1:battery_count) {
      savings_import <- mat_pv_savings_import[i,j,]
      savings_export <- mat_pv_savings_export[i,j,]
      v_savings_yrs <- savings_import * tariff_info$'Import ($/kWh)' * (1 + tariff_info$'Import Inflation (%)') ^ c(0:(analysis_years-1)) + savings_export * tariff_info$'Export ($/kWh)' * (1 + tariff_info$'Export Inflation (%)') ^ c(0:(analysis_years-1))
      mat_pv_cf[i,j,] <- c(-capital_cost, v_savings_yrs)
    }
  }

  mat_battery_cf <- array(0, dim=c(pv_count, battery_count, analysis_years+1))
  for (j in 1:battery_count) {
    capital_cost <- v_battery_cost[j]
    for (i in 1:pv_count) {
      savings_import <- mat_battery_savings_import[i,j,]
      savings_export <- mat_battery_savings_export[i,j,]
      v_savings_yrs <- savings_import * tariff_info$'Import ($/kWh)' * (1 + tariff_info$'Import Inflation (%)') ^ c(0:(analysis_years-1)) + savings_export * tariff_info$'Export ($/kWh)' * (1 + tariff_info$'Export Inflation (%)') ^ c(0:(analysis_years-1))
      mat_battery_cf[i,j,] <- c(-capital_cost, v_savings_yrs)
    }
  }

  mat_system_cf <- array(0, dim=c(pv_count, battery_count, analysis_years+1))
  for (i in 1:pv_count) {
    for (j in 1:battery_count) {
      capital_cost <- mat_system_cost[i,j]
      savings_import <- mat_system_savings_import[i,j,]
      savings_export <- mat_system_savings_export[i,j,]
      v_savings_yrs <- savings_import * tariff_info$'Import ($/kWh)' * (1 + tariff_info$'Import Inflation (%)') ^ c(0:(analysis_years-1)) + savings_export * tariff_info$'Export ($/kWh)' * (1 + tariff_info$'Export Inflation (%)') ^ c(0:(analysis_years-1))
      mat_system_cf[i,j,] <- c(-capital_cost, v_savings_yrs)
    }
  }

  if (timing) {
    print(paste("--> Cash flow calculated:", round(now() - time_a,2), "seconds"))
    time_a <- now()
  }

  # Payback (discounted) calculation: PV, Battery, System
  # ------------------------------------------------------
  mat_pv_pbt <- matrix(0, nrow=pv_count, ncol=battery_count)
  mat_battery_pbt <- matrix(0, nrow=pv_count, ncol=battery_count)
  mat_system_pbt <- matrix(0, nrow=pv_count, ncol=battery_count)
  for (i in 1:pv_count) {
    for (j in 1:battery_count) {
      mat_pv_pbt[i,j] <- dpb(finance_info$'Discount Rate (%)', mat_pv_cf[i,j,])
      mat_battery_pbt[i,j] <- dpb(finance_info$'Discount Rate (%)', mat_battery_cf[i,j,])
      mat_system_pbt[i,j] <- dpb(finance_info$'Discount Rate (%)', mat_system_cf[i,j,])
    }
  }

  if (timing) {
    print(paste("--> Discounted Payback calculated:", round(now() - time_a,2), "seconds"))
    time_a <- now()
  }

  # NPV calculation: PV, Battery, System
  # ------------------------------------
  mat_pv_npv <- matrix(0, nrow=pv_count, ncol=battery_count)
  mat_battery_npv <- matrix(0, nrow=pv_count, ncol=battery_count)
  mat_system_npv <- matrix(0, nrow=pv_count, ncol=battery_count)
  for (i in 1:pv_count) {
    for (j in 1:battery_count) {
      mat_pv_npv[i,j] <- npv(finance_info$'Discount Rate (%)', mat_pv_cf[i,j,])
      mat_battery_npv[i,j] <- npv(finance_info$'Discount Rate (%)', mat_battery_cf[i,j,])
      mat_system_npv[i,j] <- npv(finance_info$'Discount Rate (%)', mat_system_cf[i,j,])
    }
  }

  if (timing) {
    print(paste("--> NPV calculated:", round(now() - time_a,2), "seconds"))
    time_a <- now()
  }

  # Profit Index calculation: PV, Battery, System
  # ---------------------------------------------
  mat_pv_PI <- 1 + (mat_pv_npv / matrix(v_pv_cost, nrow=pv_count, ncol=battery_count))
  mat_battery_PI <- 1 + (mat_battery_npv / matrix(v_battery_cost, nrow=pv_count, ncol=battery_count, byrow=TRUE))
  mat_system_PI <- 1 + (mat_system_npv / mat_system_cost)

  # Internal Rate of Return calculation: PV, Battery, System
  # --------------------------------------------------------
  mat_pv_irr <- matrix(NaN, nrow=pv_count, ncol=battery_count)
  mat_battery_irr <- matrix(NaN, nrow=pv_count, ncol=battery_count)
  mat_system_irr <- matrix(NaN, nrow=pv_count, ncol=battery_count)
  if (runIRR) {
    for (i in 1:pv_count) {
      for (j in 1:battery_count) {
        if (mat_pv_npv[i,j] > 0) { mat_pv_irr[i,j] <- tryCatch(irr(mat_pv_cf[i,j,]), error=function(e) {NaN}) }
        if (mat_battery_npv[i,j] > 0) { mat_battery_irr[i,j] <- tryCatch(irr(mat_battery_cf[i,j,]), error=function(e) {NaN}) }
        if (mat_system_npv[i,j] > 0) { mat_system_irr[i,j] <- tryCatch(irr(mat_system_cf[i,j,]), error=function(e) {NaN}) }
      }
    }
  }

  if (timing) {
    print(paste("--> IRR calculated:", round(now() - time_a,2), "seconds"))
    time_a <- now()
    print(paste("====> COMPLETED <====="))
    print(round(now() - start_time))
  }

  # Combine results for global output
  return(list(Inputs = inputs,
              PV.Costs = v_pv_cost,
              Battery.Costs = v_battery_cost,
              System.Costs = mat_system_cost,
              PV.Savings = round(mat_pv_savings, 2),
              Battery.Savings = round(mat_battery_savings, 2),
              System.Savings = round(mat_system_savings, 2),
              PV.Payback = mat_pv_pbt,
              Battery.Payback = mat_battery_pbt,
              System.Payback = mat_system_pbt,
              PV.CashFlow = mat_pv_cf,
              Battery.CashFlow = mat_battery_cf,
              System.CashFlow = mat_system_cf,
              PV.NPV = round(mat_pv_npv, 2),
              Battery.NPV = round(mat_battery_npv, 2),
              System.NPV = round(mat_system_npv, 2),
              PV.PI = mat_pv_PI,
              Battery.PI = mat_battery_PI,
              System.PI = mat_system_PI,
              PV.IRR = round(mat_pv_irr, 4),
              Battery.IRR = round(mat_battery_irr, 4),
              System.IRR = round(mat_system_irr, 4)))
}