#' @tool_code ST_DESCRIPTIVE
#' @name 描述性统计
#' @version 1.0.0
#' @description 数据概况与基线特征表
#' @author SSA-Pro Team

library(glue)
library(ggplot2)
library(base64enc)

run_analysis <- function(input) {
  # ===== 初始化 =====
  logs <- c()
  log_add <- function(msg) { logs <<- c(logs, paste0("[", Sys.time(), "] ", msg)) }
  
  on.exit({}, add = TRUE)
  
  # ===== 数据加载 =====
  log_add("开始加载输入数据")
  df <- tryCatch(
    load_input_data(input),
    error = function(e) {
      log_add(paste("数据加载失败:", e$message))
      return(NULL)
    }
  )
  
  if (is.null(df)) {
    return(make_error(ERROR_CODES$E100_INTERNAL_ERROR, details = "数据加载失败"))
  }
  log_add(glue("数据加载成功: {nrow(df)} 行, {ncol(df)} 列"))
  
  p <- input$params
  variables <- p$variables  # 变量列表（可选，空则分析全部）
  group_var <- p$group_var  # 分组变量（可选）
  
  # ===== 确定要分析的变量 =====
  if (is.null(variables) || length(variables) == 0) {
    variables <- names(df)
    log_add("未指定变量，分析全部列")
  }
  
  # 排除分组变量本身
  if (!is.null(group_var) && group_var %in% variables) {
    variables <- setdiff(variables, group_var)
  }
  
  # 校验变量存在性
  missing_vars <- setdiff(variables, names(df))
  if (length(missing_vars) > 0) {
    return(make_error(ERROR_CODES$E001_COLUMN_NOT_FOUND, 
                      col = paste(missing_vars, collapse = ", ")))
  }
  
  # 校验分组变量
  groups <- NULL
  if (!is.null(group_var) && group_var != "") {
    if (!(group_var %in% names(df))) {
      return(make_error(ERROR_CODES$E001_COLUMN_NOT_FOUND, col = group_var))
    }
    groups <- unique(df[[group_var]][!is.na(df[[group_var]])])
    log_add(glue("分组变量: {group_var}, 分组: {paste(groups, collapse=', ')}"))
  }
  
  # ===== 变量类型推断 =====
  var_types <- sapply(variables, function(v) {
    vals <- df[[v]]
    if (is.numeric(vals)) {
      non_na_count <- sum(!is.na(vals))
      if (non_na_count == 0) {
        return("categorical")  # 全是 NA，当作分类变量
      }
      unique_count <- length(unique(vals[!is.na(vals)]))
      unique_ratio <- unique_count / non_na_count
      if (unique_ratio < 0.05 && unique_count <= 10) {
        return("categorical")
      }
      return("numeric")
    } else {
      return("categorical")
    }
  })
  
  log_add(glue("数值变量: {sum(var_types == 'numeric')}, 分类变量: {sum(var_types == 'categorical')}"))
  
  # ===== 计算描述性统计 =====
  warnings_list <- c()
  results_list <- list()
  
  for (v in variables) {
    var_type <- as.character(var_types[v])
    if (is.na(var_type) || length(var_type) == 0) {
      var_type <- "categorical"  # 默认为分类变量
    }
    
    if (is.null(groups)) {
      # 无分组
      if (identical(var_type, "numeric")) {
        stats <- calc_numeric_stats(df[[v]], v)
      } else {
        stats <- calc_categorical_stats(df[[v]], v)
      }
      stats$type <- var_type
      results_list[[v]] <- stats
    } else {
      # 有分组
      group_stats <- list()
      for (g in groups) {
        subset_vals <- df[df[[group_var]] == g, v, drop = TRUE]
        if (identical(var_type, "numeric")) {
          group_stats[[as.character(g)]] <- calc_numeric_stats(subset_vals, v)
        } else {
          group_stats[[as.character(g)]] <- calc_categorical_stats(subset_vals, v)
        }
      }
      results_list[[v]] <- list(
        variable = v,
        type = var_type,
        by_group = group_stats
      )
    }
  }
  
  # ===== 总体概况 =====
  summary_stats <- list(
    n_total = nrow(df),
    n_variables = length(variables),
    n_numeric = sum(var_types == "numeric"),
    n_categorical = sum(var_types == "categorical")
  )
  
  if (!is.null(groups)) {
    summary_stats$group_var <- group_var
    summary_stats$groups <- lapply(groups, function(g) {
      list(name = as.character(g), n = sum(df[[group_var]] == g, na.rm = TRUE))
    })
  }
  
  # ===== 生成图表 =====
  log_add("生成描述性统计图表")
  plots <- list()
  
  # 只为前几个变量生成图表（避免过多）
  vars_to_plot <- head(variables, 4)
  
  for (v in vars_to_plot) {
    plot_base64 <- tryCatch({
      if (var_types[v] == "numeric") {
        generate_histogram(df, v, group_var)
      } else {
        generate_bar_chart(df, v, group_var)
      }
    }, error = function(e) {
      log_add(paste("图表生成失败:", v, e$message))
      NULL
    })
    
    if (!is.null(plot_base64)) {
      plots <- c(plots, list(plot_base64))
    }
  }
  
  # ===== 生成可复现代码 =====
  original_filename <- if (!is.null(input$original_filename) && nchar(input$original_filename) > 0) {
    input$original_filename
  } else {
    "data.csv"
  }
  
  reproducible_code <- glue('
# SSA-Pro 自动生成代码
# 工具: 描述性统计
# 时间: {Sys.time()}
# ================================

library(ggplot2)

# 数据准备
df <- read.csv("{original_filename}")

# 数值变量描述性统计
numeric_vars <- sapply(df, is.numeric)
if (any(numeric_vars)) {{
  summary(df[, numeric_vars, drop = FALSE])
}}

# 分类变量频数表
categorical_vars <- !numeric_vars
if (any(categorical_vars)) {{
  for (v in names(df)[categorical_vars]) {{
    cat("\\n变量:", v, "\\n")
    print(table(df[[v]], useNA = "ifany"))
  }}
}}

# 可视化示例
# ggplot(df, aes(x = your_variable)) + geom_histogram()
')
  
  # ===== 返回结果 =====
  log_add("分析完成")
  
  return(list(
    status = "success",
    message = "分析完成",
    warnings = if (length(warnings_list) > 0) warnings_list else NULL,
    results = list(
      summary = summary_stats,
      variables = results_list
    ),
    plots = plots,
    trace_log = logs,
    reproducible_code = as.character(reproducible_code)
  ))
}

# ===== 辅助函数 =====

# 数值变量统计
calc_numeric_stats <- function(vals, var_name) {
  vals <- vals[!is.na(vals)]
  n <- length(vals)
  
  if (n == 0) {
    return(list(
      variable = var_name,
      n = 0,
      missing = length(vals) - n,
      stats = NULL
    ))
  }
  
  list(
    variable = var_name,
    n = n,
    missing = 0,
    mean = round(mean(vals), 3),
    sd = round(sd(vals), 3),
    median = round(median(vals), 3),
    q1 = round(quantile(vals, 0.25), 3),
    q3 = round(quantile(vals, 0.75), 3),
    iqr = round(IQR(vals), 3),
    min = round(min(vals), 3),
    max = round(max(vals), 3),
    skewness = round(calc_skewness(vals), 3),
    formatted = paste0(round(mean(vals), 2), " ± ", round(sd(vals), 2))
  )
}

# 分类变量统计
calc_categorical_stats <- function(vals, var_name) {
  total <- length(vals)
  valid <- sum(!is.na(vals))
  
  freq_table <- table(vals, useNA = "no")
  
  levels_list <- lapply(names(freq_table), function(level) {
    count <- as.numeric(freq_table[level])
    pct <- round(count / valid * 100, 1)
    list(
      level = level,
      n = count,
      pct = pct,
      formatted = paste0(count, " (", pct, "%)")
    )
  })
  
  list(
    variable = var_name,
    n = valid,
    missing = total - valid,
    levels = levels_list
  )
}

# 计算偏度
calc_skewness <- function(x) {
  n <- length(x)
  if (n < 3) return(NA)
  m <- mean(x)
  s <- sd(x)
  sum((x - m)^3) / (n * s^3)
}

# 生成直方图
generate_histogram <- function(df, var_name, group_var = NULL) {
  if (!is.null(group_var) && group_var != "") {
    p <- ggplot(df[!is.na(df[[var_name]]), ], aes(x = .data[[var_name]], fill = factor(.data[[group_var]]))) +
      geom_histogram(alpha = 0.6, position = "identity", bins = 30) +
      scale_fill_brewer(palette = "Set1", name = group_var) +
      theme_minimal()
  } else {
    p <- ggplot(df[!is.na(df[[var_name]]), ], aes(x = .data[[var_name]])) +
      geom_histogram(fill = "#3b82f6", alpha = 0.7, bins = 30) +
      theme_minimal()
  }
  
  p <- p + labs(title = paste("Distribution of", var_name), x = var_name, y = "Count")
  
  tmp_file <- tempfile(fileext = ".png")
  ggsave(tmp_file, p, width = 6, height = 4, dpi = 100)
  base64_str <- base64encode(tmp_file)
  unlink(tmp_file)
  
  return(paste0("data:image/png;base64,", base64_str))
}

# 生成柱状图
generate_bar_chart <- function(df, var_name, group_var = NULL) {
  df_plot <- df[!is.na(df[[var_name]]), ]
  
  if (!is.null(group_var) && group_var != "") {
    p <- ggplot(df_plot, aes(x = factor(.data[[var_name]]), fill = factor(.data[[group_var]]))) +
      geom_bar(position = "dodge") +
      scale_fill_brewer(palette = "Set1", name = group_var) +
      theme_minimal()
  } else {
    p <- ggplot(df_plot, aes(x = factor(.data[[var_name]]))) +
      geom_bar(fill = "#3b82f6", alpha = 0.7) +
      theme_minimal()
  }
  
  p <- p + labs(title = paste("Frequency of", var_name), x = var_name, y = "Count") +
    theme(axis.text.x = element_text(angle = 45, hjust = 1))
  
  tmp_file <- tempfile(fileext = ".png")
  ggsave(tmp_file, p, width = 6, height = 4, dpi = 100)
  base64_str <- base64encode(tmp_file)
  unlink(tmp_file)
  
  return(paste0("data:image/png;base64,", base64_str))
}