library(shiny)
library(DBI)
library(RPostgres)
library(dplyr)
library(DT)
library(glue)

pg_dsn <- Sys.getenv("PG_DSN", "")
s3_bucket <- Sys.getenv("S3_BUCKET", "")
s3_endpoint <- Sys.getenv("S3_ENDPOINT", Sys.getenv("AWS_S3_ENDPOINT", Sys.getenv("AWS_S3_ENDPOINT_URL", "")))
aws_access_key <- Sys.getenv("S3_ACCESS_KEY", Sys.getenv("AWS_ACCESS_KEY_ID", ""))
aws_secret_key <- Sys.getenv("S3_SECRET_KEY", Sys.getenv("AWS_SECRET_ACCESS_KEY", ""))
aws_cli <- Sys.getenv("AWS_CLI", "aws")
thumb_prefix <- Sys.getenv("THUMB_PREFIX", "icu/thumbnails/")
processed_prefix <- Sys.getenv("PROCESSED_PREFIX", "icu/processed/")
entrance_prefix <- Sys.getenv("ENTRANCE_PREFIX", "icu/entrance/")
processed_prefix <- Sys.getenv("PROCESSED_PREFIX", "icu/processed/")
thumb_prefix <- Sys.getenv("THUMB_PREFIX", "icu/thumbnails/")

inventory_table <- Sys.getenv("INVENTORY_TABLE", "")
deployment_table <- Sys.getenv("DEPLOYMENT_TABLE", "")

if (pg_dsn == "") {
  stop("PG_DSN env var is required")
}
if (s3_bucket == "") {
  stop("S3_BUCKET env var is required")
}
if (s3_endpoint == "") {
  stop("S3_ENDPOINT/AWS_S3_ENDPOINT env var is required")
}
if (aws_access_key == "" || aws_secret_key == "") {
  stop("S3_ACCESS_KEY/S3_SECRET_KEY or AWS_ACCESS_KEY_ID/AWS_SECRET_ACCESS_KEY required")
}

Sys.setenv(
  AWS_ACCESS_KEY_ID = aws_access_key,
  AWS_SECRET_ACCESS_KEY = aws_secret_key,
  AWS_EC2_METADATA_DISABLED = "true"
)

parse_pg_dsn <- function(dsn) {
  if (grepl("^postgresql://", dsn)) {
    m <- regexec("^postgresql://([^:]+):([^@]+)@([^:/]+):?(\\d+)?/(.+)$", dsn)
    r <- regmatches(dsn, m)[[1]]
    if (length(r) == 0) stop("Invalid PG_DSN URL format")
    return(list(
      user = r[2],
      password = r[3],
      host = r[4],
      port = ifelse(r[5] == "", 5432, as.integer(r[5])),
      dbname = r[6]
    ))
  }

  if (grepl("host=", dsn)) {
    parts <- strsplit(dsn, "\\s+")[[1]]
    kv <- lapply(parts, function(p) strsplit(p, "=", fixed = TRUE)[[1]])
    vals <- setNames(lapply(kv, `[`, 2), lapply(kv, `[`, 1))
    return(list(
      user = vals$user,
      password = vals$password,
      host = vals$host,
      port = as.integer(vals$port),
      dbname = vals$dbname
    ))
  }

  return(list(dbname = dsn))
}

pg <- parse_pg_dsn(pg_dsn)
pg_con <- do.call(dbConnect, c(list(RPostgres::Postgres()), pg))
onStop(function() dbDisconnect(pg_con))

table_exists <- function(con, table_name) {
  res <- dbGetQuery(con, "SELECT to_regclass($1) AS t", params = list(table_name))
  !is.na(res$t[1])
}

fetch_cameras <- function() {
  if (inventory_table != "" && table_exists(pg_con, inventory_table)) {
    q <- glue("SELECT DISTINCT cam_id FROM {inventory_table} ORDER BY 1")
    return(dbGetQuery(pg_con, q)$cam_id)
  }
  character(0)
}

fetch_projects <- function() {
  if (deployment_table != "" && table_exists(pg_con, deployment_table)) {
    q <- glue("SELECT DISTINCT project FROM {deployment_table} ORDER BY 1")
    return(dbGetQuery(pg_con, q)$project)
  }
  character(0)
}

build_query <- function(from_date, to_date, camera_id, project_name, limit_rows, offset_rows, use_date_filter) {
  base <- "
    SELECT
      m.metadata_uuid,
      m.import_ts,
      m.ocr_ts,
      m.\"CustomerTimezone\",
      m.\"SignalStrength\",
      m.\"Temperature\",
      m.imei,
      m.servertime,
      ci.cam_id,
      d.project,
      c.category,
      c.score
    FROM remote_cam.metadata m
    LEFT JOIN cam_inventory ci ON ci.imei = m.imei
    LEFT JOIN LATERAL (
      SELECT d.project
        FROM cam_deployments d
       WHERE d.camera_id = ci.cam_id
         AND m.servertime >= d.deployment_start
         AND (d.deployment_end IS NULL OR m.servertime < d.deployment_end)
       ORDER BY d.deployment_start DESC NULLS LAST
       LIMIT 1
    ) d ON TRUE
    LEFT JOIN LATERAL (
      SELECT category, score
        FROM remote_cam.category c
       WHERE c.image_uuid = m.metadata_uuid
       ORDER BY score DESC NULLS LAST
       LIMIT 1
    ) c ON TRUE
  "

  params <- list()

  if (camera_id != "" && inventory_table != "" && table_exists(pg_con, inventory_table)) {
    base <- paste0(base, " WHERE ci.cam_id = $", length(params) + 1)
    params <- append(params, list(camera_id))
  }

  if (project_name != "" && deployment_table != "" && table_exists(pg_con, deployment_table)) {
    prefix <- if (length(params) == 0) " WHERE " else " AND "
    base <- paste0(base, prefix, " m.imei IN (SELECT ci2.imei FROM cam_inventory ci2 JOIN ",
                   deployment_table, " d ON d.camera_id = ci2.cam_id WHERE d.project = $",
                   length(params) + 1, ")")
    params <- append(params, list(project_name))
  }

  if (camera_id == "" && project_name == "" && !use_date_filter) {
    base <- paste0(base, " ORDER BY m.import_ts DESC LIMIT $", length(params) + 1, " OFFSET $", length(params) + 2)
    params <- append(params, list(as.integer(limit_rows), as.integer(offset_rows)))
    return(list(sql = base, params = params))
  }

  if (use_date_filter) {
    prefix <- if (length(params) == 0) " WHERE " else " AND "
    base <- paste0(base, prefix, " m.import_ts >= $", length(params) + 1, " AND m.import_ts < $", length(params) + 2)
    params <- append(params, list(from_date, to_date))
  }

  base <- paste0(base, " ORDER BY m.import_ts DESC LIMIT $", length(params) + 1, " OFFSET $", length(params) + 2)
  params <- append(params, list(as.integer(limit_rows), as.integer(offset_rows)))
  list(sql = base, params = params)
}

normalize_endpoint <- function(url) {
  if (url == "") return("")
  u <- url
  if (!grepl("^https?://", u)) {
    u <- paste0("https://", u)
  }
  sub("/+$", "", u)
}

s3_endpoint <- normalize_endpoint(s3_endpoint)

if (aws_access_key == "" || aws_secret_key == "" || s3_endpoint == "") {
  stop("S3_ACCESS_KEY/S3_SECRET_KEY or AWS_ACCESS_KEY_ID/AWS_SECRET_ACCESS_KEY and S3_ENDPOINT are required")
}

normalize_endpoint <- function(url) {
  if (url == "") return("")
  u <- url
  if (!grepl("^https?://", u)) {
    u <- paste0("https://", u)
  }
  sub("/+$", "", u)
}

s3_endpoint <- normalize_endpoint(s3_endpoint)
cache_dir <- Sys.getenv("THUMB_CACHE_DIR", "/tmp/thumb_cache")
dir.create(cache_dir, recursive = TRUE, showWarnings = FALSE)
addResourcePath("thumbs", cache_dir)

presigned_url <- function(key, expires = 600) {
  if (is.null(key) || is.na(key) || key == "") return(NULL)
  key <- sub(paste0("^", s3_bucket, "/"), "", key)
  cmd <- sprintf(
    "\"%s\" --endpoint-url %s s3 presign s3://%s/%s --expires-in %d",
    aws_cli, s3_endpoint, s3_bucket, key, as.integer(expires)
  )
  tryCatch({
    out <- system(cmd, intern = TRUE)
    if (length(out) == 0) return(NULL)
    out[1]
  }, error = function(e) {
    message(sprintf("[DEBUG] presign error: %s", e$message))
    NULL
  })
}

cache_thumbnail <- function(uuid) {
  if (is.null(uuid) || is.na(uuid)) return(NULL)
  local_path <- file.path(cache_dir, paste0(uuid, ".jpg"))
  if (file.exists(local_path)) return(local_path)
  key <- paste0(thumb_prefix, uuid, ".jpg")
  cmd <- sprintf(
    "\"%s\" --endpoint-url %s s3 cp s3://%s/%s \"%s\" --only-show-errors",
    aws_cli, s3_endpoint, s3_bucket, key, local_path
  )
  tryCatch({
    system(cmd, ignore.stdout = TRUE, ignore.stderr = TRUE)
    if (file.exists(local_path)) return(local_path)
    NULL
  }, error = function(e) {
    message(sprintf("[DEBUG] cache thumb error: %s", e$message))
    NULL
  })
}

ui <- fluidPage(
  titlePanel("MelesICU - Image Browser"),
  tags$script(HTML("
    function melesThumbClick(el){
      var uuid = el.getAttribute('data-uuid');
      if(uuid){
        Shiny.setInputValue('thumb_click', uuid, {priority: 'event'});
      }
    }
    var melesScrollLock = false;
    window.addEventListener('scroll', function() {
      if (melesScrollLock) return;
      var nearBottom = (window.innerHeight + window.scrollY) >= (document.body.offsetHeight - 200);
      var canLoad = Shiny && Shiny.shinyapp && Shiny.shinyapp.$outputValues && Shiny.shinyapp.$outputValues.has_more_flag;
      var isLoading = Shiny && Shiny.shinyapp && Shiny.shinyapp.$outputValues && Shiny.shinyapp.$outputValues.loading_flag;
      if (nearBottom && canLoad && !isLoading) {
        melesScrollLock = true;
        Shiny.setInputValue('scroll_load', Date.now(), {priority: 'event'});
        setTimeout(function(){ melesScrollLock = false; }, 1000);
      }
    });
  ")),
  sidebarLayout(
    sidebarPanel(
      dateRangeInput("date_range", "Datum", start = Sys.Date() - 7, end = Sys.Date()),
      checkboxInput("use_date_filter", "Datumsfilter aktiv", value = TRUE),
      selectInput("camera_id", "Kamera (cam_id)", choices = c("ALL", fetch_cameras()), selected = "ALL"),
      selectInput("project_name", "Projekt", choices = c("ALL", fetch_projects()), selected = "ALL"),
      numericInput("limit_rows", "Eintraege pro Seite", value = 20, min = 10, max = 2000, step = 10),
      numericInput("page", "Seite", value = 1, min = 1, step = 1),
      fluidRow(
        column(6, actionButton("prev_page", "Zurueck")),
        column(6, actionButton("next_page", "Vor"))
      ),
      actionButton("apply_filters", "Filter anwenden")
    ),
    mainPanel(
      tags$style(HTML("
        .spinner {
          margin: 20px 0;
          width: 32px;
          height: 32px;
          border: 4px solid #ddd;
          border-top-color: #333;
          border-radius: 50%;
          animation: spin 1s linear infinite;
        }
        @keyframes spin { to { transform: rotate(360deg); } }
      ")),
      conditionalPanel("output.loading_flag", tags$div(class = "spinner")),
      uiOutput("debug_info"),
      uiOutput("thumb_grid")
    )
  )
)

server <- function(input, output, session) {
  rv <- reactiveValues(data = NULL, selected = NULL, loading = FALSE, has_more = TRUE, debug = NULL)
  cache_env <- new.env(parent = emptyenv())
  cache_keys <- character(0)
  url_cache_env <- new.env(parent = emptyenv())
  url_cache_keys <- character(0)

  load_data <- function() {
    from_date <- as.POSIXct(input$date_range[1], tz = "UTC")
    to_date <- as.POSIXct(input$date_range[2] + 1, tz = "UTC")
    cam <- ifelse(input$camera_id == "ALL", "", input$camera_id)
    proj <- ifelse(input$project_name == "ALL", "", input$project_name)
    page <- max(1, as.integer(input$page))
    limit <- as.integer(input$limit_rows)
    offset <- (page - 1) * limit

    key <- paste(from_date, to_date, cam, proj, input$use_date_filter, limit, offset, sep = "|")
    if (exists(key, envir = cache_env, inherits = FALSE)) {
      rv$data <- get(key, envir = cache_env, inherits = FALSE)
      return(invisible(NULL))
    }

    q <- build_query(from_date, to_date, cam, proj, limit, offset, input$use_date_filter)
    rv$loading <- TRUE
    on.exit({ rv$loading <- FALSE }, add = TRUE)
    data <- dbGetQuery(pg_con, q$sql, params = q$params)
    assign(key, data, envir = cache_env)
    cache_keys <<- c(cache_keys, key)
    if (length(cache_keys) > 20) {
      drop <- head(cache_keys, length(cache_keys) - 20)
      for (k in drop) rm(list = k, envir = cache_env)
      cache_keys <<- tail(cache_keys, 20)
    }
    rv$data <- data
    rv$has_more <- nrow(data) >= limit

    # Batch prefetch first 10 thumbnails in parallel
    if (!is.null(data) && nrow(data) > 0) {
      uuids <- head(data$metadata_uuid, 10)
      tryCatch({
        parallel::mclapply(uuids, cache_thumbnail, mc.cores = 4)
      }, error = function(e) {
        message(sprintf("[DEBUG] prefetch error: %s", e$message))
      })
    }

    if (!is.null(data) && nrow(data) > 0) {
      sample_uuid <- data$metadata_uuid[1]
      thumb_key <- paste0(thumb_prefix, sample_uuid, ".jpg")
      url <- presigned_url(thumb_key)
      rv$debug <- list(
        count = nrow(data),
        sample_uuid = sample_uuid,
        thumb_key = thumb_key,
        url = url
      )
      message(sprintf("[DEBUG] count=%d sample_uuid=%s thumb_key=%s url=%s",
                      nrow(data), sample_uuid, thumb_key, ifelse(is.null(url), "NULL", url)))
    } else {
      rv$debug <- list(count = 0)
      message("[DEBUG] count=0")
    }
  }

  observeEvent(input$apply_filters, {
    if (rv$loading) {
      showNotification("Noch am Laden – bitte warten.", type = "message")
      return(NULL)
    }
    load_data()
  }, ignoreInit = TRUE)

  observeEvent(input$prev_page, {
    if (rv$loading) return(NULL)
    new_page <- max(1, as.integer(input$page) - 1)
    updateNumericInput(session, "page", value = new_page)
    load_data()
  }, ignoreInit = TRUE)

  observeEvent(input$next_page, {
    if (rv$loading) return(NULL)
    new_page <- as.integer(input$page) + 1
    updateNumericInput(session, "page", value = new_page)
    load_data()
  }, ignoreInit = TRUE)

  observeEvent(input$scroll_load, {
    if (rv$loading || !rv$has_more) return(NULL)
    new_page <- as.integer(input$page) + 1
    updateNumericInput(session, "page", value = new_page)
    load_data()
  }, ignoreInit = TRUE)

  observeEvent(TRUE, {
    if (rv$loading) return(NULL)
    load_data()
  }, once = TRUE)

  output$loading_flag <- reactive({ rv$loading })
  outputOptions(output, "loading_flag", suspendWhenHidden = FALSE)

  output$has_more_flag <- reactive({ rv$has_more })
  outputOptions(output, "has_more_flag", suspendWhenHidden = FALSE)

  format_cet <- function(ts) {
    if (is.null(ts) || is.na(ts)) return("-")
    format(as.POSIXct(ts, tz = "CET"), "%Y-%m-%d %H:%M:%S %Z")
  }

  format_ts <- function(ts) {
    if (is.null(ts) || is.na(ts)) return("-")
    format(as.POSIXct(ts, tz = "CET"), "%Y-%m-%d %H:%M:%S %Z")
  }

  format_diff <- function(server_ts, camera_ts) {
    if (is.null(server_ts) || is.na(server_ts) || is.null(camera_ts) || is.na(camera_ts)) return("-")
    secs <- as.numeric(difftime(server_ts, camera_ts, units = "secs"))
    sign <- ifelse(secs >= 0, "+", "-")
    secs <- abs(secs)
    hh <- floor(secs / 3600)
    mm <- floor((secs %% 3600) / 60)
    ss <- floor(secs %% 60)
    sprintf("%s%02d:%02d:%02d", sign, hh, mm, ss)
  }

  output$thumb_grid <- renderUI({
    dat <- rv$data
    if (is.null(dat) || nrow(dat) == 0) {
      return(tags$div("Keine Ergebnisse."))
    }

    cards <- lapply(seq_len(nrow(dat)), function(i) {
      row <- dat[i, ]
      local_path <- cache_thumbnail(row$metadata_uuid)
      if (is.null(local_path)) return(NULL)
      url <- paste0("thumbs/", basename(local_path))
      tags$div(
        style = "display:inline-block; width: 220px; margin: 6px; vertical-align: top;",
        tags$div(class = "ph", style = "width: 220px; height: 220px; background:#eee; display:block;"),
        tags$img(
          src = url,
          style = "width: 220px; height: 220px; object-fit: cover; display:block; cursor: pointer;",
          loading = "lazy",
          onload = "this.parentNode.querySelector('.ph').style.display='none';",
          `data-uuid` = row$metadata_uuid,
          onclick = "melesThumbClick(this)"
        ),
        tags$div(style = "font-size: 12px; color: #222;",
                 glue("CamID: {row$cam_id}")),
        tags$div(style = "font-size: 12px; color: #444;",
                 glue("Serverzeit: {format_cet(row$servertime)}")),
        tags$div(style = "font-size: 12px; color: #444;",
                 glue("Kamerazeit: {format_ts(row$ocr_ts)}")),
        tags$div(style = "font-size: 12px; color: #444;",
                 glue("AI classification: {row$category} ({row$score})")),
        {
          delta <- format_diff(row$servertime, row$ocr_ts)
          delta_secs <- if (delta == "-") NA else as.numeric(difftime(row$servertime, row$ocr_ts, units = "secs"))
          is_warn <- !is.na(delta_secs) && abs(delta_secs) > 600
          style <- if (is_warn) "font-size: 12px; color: #c00; font-weight: bold;" else "font-size: 12px; color: #444;"
          tags$div(style = style, glue("Delta: {delta}"))
        }
      )
    })

    tags$div(cards)
  })

  output$debug_info <- renderUI({
    if (is.null(rv$debug)) return(NULL)
    cnt <- rv$debug$count
    if (is.null(cnt)) return(NULL)
    if (cnt == 0) {
      return(tags$div(style = "font-size:12px; color:#a00; margin-bottom:8px;",
                      "Debug: 0 Treffer."))
    }
    tags$div(style = "font-size:12px; color:#555; margin-bottom:8px;",
             glue("Debug: Treffer={cnt}, Sample UUID={rv$debug$sample_uuid}"),
             tags$br(),
             glue("Thumb-Key: {rv$debug$thumb_key}"),
             tags$br(),
             if (!is.null(rv$debug$url)) tags$a(href = rv$debug$url, "Sample Thumbnail (Link)", target = "_blank") else "Sample URL: NULL")
  })

  observeEvent(input$thumb_click, {
    uuid <- input$thumb_click
    dat <- rv$data
    if (is.null(dat)) return(NULL)
    row <- dat[dat$metadata_uuid == uuid, ]
    if (nrow(row) != 1) return(NULL)
    full_key <- paste0(processed_prefix, row$metadata_uuid, ".jpg")
    presigned_cached <- function(key, expires = 600) {
      now <- Sys.time()
      if (exists(key, envir = url_cache_env, inherits = FALSE)) {
        entry <- get(key, envir = url_cache_env, inherits = FALSE)
        if (is.list(entry) && !is.null(entry$expires_at) && now < entry$expires_at) {
          return(entry$url)
        }
      }
      u <- presigned_url(key, expires = expires)
      if (!is.null(u)) {
        assign(key, list(url = u, expires_at = now + expires - 30), envir = url_cache_env)
        url_cache_keys <<- c(url_cache_keys, key)
        if (length(url_cache_keys) > 200) {
          drop <- head(url_cache_keys, length(url_cache_keys) - 200)
          for (k in drop) rm(list = k, envir = url_cache_env)
          url_cache_keys <<- tail(url_cache_keys, 200)
        }
      }
      u
    }

    url <- presigned_cached(full_key)
    if (is.null(url)) {
      showModal(modalDialog(
        title = glue("Bild {uuid}"),
        "Full image nicht gefunden.",
        easyClose = TRUE,
        footer = NULL
      ))
      return(NULL)
    }
    showModal(modalDialog(
      title = glue("Bild {uuid}"),
      tags$img(src = url, style = "max-width: 100%; height: auto;"),
      easyClose = TRUE,
      footer = modalButton("Schließen"),
      size = "l"
    ))
  })
}

shinyApp(ui, server)