local log = require('pending.log')
local util = require('pending.sync.util')

local M = {}

M.name = 's3'

---@return pending.S3Config?
local function get_config()
  local cfg = require('pending.config').get()
  return cfg.sync and cfg.sync.s3
end

---@return string[]
local function base_cmd()
  local s3cfg = get_config() or {}
  local cmd = { 'aws' }
  if s3cfg.profile then
    table.insert(cmd, '--profile')
    table.insert(cmd, s3cfg.profile)
  end
  if s3cfg.region then
    table.insert(cmd, '--region')
    table.insert(cmd, s3cfg.region)
  end
  return cmd
end

---@param task pending.Task
---@return string
local function ensure_sync_id(task)
  if not task._extra then
    task._extra = {}
  end
  local sync_id = task._extra['_s3_sync_id']
  if not sync_id then
    local bytes = {}
    math.randomseed(vim.uv.hrtime())
    for i = 1, 16 do
      bytes[i] = math.random(0, 255)
    end
    bytes[7] = bit.bor(bit.band(bytes[7], 0x0f), 0x40)
    bytes[9] = bit.bor(bit.band(bytes[9], 0x3f), 0x80)
    sync_id = string.format(
      '%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x',
      bytes[1], bytes[2], bytes[3], bytes[4],
      bytes[5], bytes[6],
      bytes[7], bytes[8],
      bytes[9], bytes[10],
      bytes[11], bytes[12], bytes[13], bytes[14], bytes[15], bytes[16]
    )
    task._extra['_s3_sync_id'] = sync_id
    task.modified = os.date('!%Y-%m-%dT%H:%M:%SZ') --[[@as string]]
  end
  return sync_id
end

---@param args? string
---@return nil
function M.auth(args)
  if args == 'profile' then
    vim.ui.input({ prompt = 'AWS profile name: ' }, function(input)
      if not input or input == '' then
        local s3cfg = get_config()
        if s3cfg and s3cfg.profile then
          log.info('s3: current profile: ' .. s3cfg.profile)
        else
          log.info('s3: no profile configured (using default)')
        end
        return
      end
      log.info('s3: set profile in your config: sync = { s3 = { profile = "' .. input .. '" } }')
    end)
    return
  end

  util.async(function()
    local cmd = base_cmd()
    vim.list_extend(cmd, { 'sts', 'get-caller-identity', '--output', 'json' })
    local result = util.system(cmd, { text = true })
    if result.code == 0 then
      local ok, data = pcall(vim.json.decode, result.stdout or '')
      if ok and data then
        log.info('s3: authenticated as ' .. (data.Arn or data.Account or 'unknown'))
      else
        log.info('s3: credentials valid')
      end
    else
      local stderr = result.stderr or ''
      if stderr:find('SSO') or stderr:find('sso') then
        log.info('s3: SSO session expired — running login...')
        local login_cmd = base_cmd()
        vim.list_extend(login_cmd, { 'sso', 'login' })
        local login_result = util.system(login_cmd, { text = true })
        if login_result.code == 0 then
          log.info('s3: SSO login successful')
        else
          log.error('s3: SSO login failed — ' .. (login_result.stderr or ''))
        end
      elseif stderr:find('Unable to locate credentials') or stderr:find('NoCredentialProviders') then
        log.error('s3: no AWS credentials configured. See :h pending-s3')
      else
        log.error('s3: ' .. stderr)
      end
    end
  end)
end

---@return string[]
function M.auth_complete()
  return { 'profile' }
end

function M.push()
  util.async(function()
    util.with_guard('s3', function()
      local s3cfg = get_config()
      if not s3cfg or not s3cfg.bucket then
        log.error('s3: bucket is required. Set sync.s3.bucket in config.')
        return
      end
      local key = s3cfg.key or 'pending.json'
      local s = require('pending').store()

      for _, task in ipairs(s:tasks()) do
        ensure_sync_id(task)
      end

      local tmpfile = vim.fn.tempname() .. '.json'
      s:save()

      local store = require('pending.store')
      local tmp_store = store.new(s.path)
      tmp_store:load()

      local f = io.open(s.path, 'r')
      if not f then
        log.error('s3: failed to read store file')
        return
      end
      local content = f:read('*a')
      f:close()

      local tf = io.open(tmpfile, 'w')
      if not tf then
        log.error('s3: failed to create temp file')
        return
      end
      tf:write(content)
      tf:close()

      local cmd = base_cmd()
      vim.list_extend(cmd, { 's3', 'cp', tmpfile, 's3://' .. s3cfg.bucket .. '/' .. key })
      local result = util.system(cmd, { text = true })
      os.remove(tmpfile)

      if result.code ~= 0 then
        log.error('s3 push: ' .. (result.stderr or 'unknown error'))
        return
      end

      util.finish(s)
      log.info('s3 push: uploaded to s3://' .. s3cfg.bucket .. '/' .. key)
    end)
  end)
end

function M.pull()
  util.async(function()
    util.with_guard('s3', function()
      local s3cfg = get_config()
      if not s3cfg or not s3cfg.bucket then
        log.error('s3: bucket is required. Set sync.s3.bucket in config.')
        return
      end
      local key = s3cfg.key or 'pending.json'
      local tmpfile = vim.fn.tempname() .. '.json'

      local cmd = base_cmd()
      vim.list_extend(cmd, { 's3', 'cp', 's3://' .. s3cfg.bucket .. '/' .. key, tmpfile })
      local result = util.system(cmd, { text = true })

      if result.code ~= 0 then
        os.remove(tmpfile)
        log.error('s3 pull: ' .. (result.stderr or 'unknown error'))
        return
      end

      local store = require('pending.store')
      local s_remote = store.new(tmpfile)
      local load_ok = pcall(function()
        s_remote:load()
      end)
      if not load_ok then
        os.remove(tmpfile)
        log.error('s3 pull: failed to parse remote store')
        return
      end

      local s = require('pending').store()
      local created, updated, unchanged = 0, 0, 0

      local local_by_sync_id = {}
      for _, task in ipairs(s:tasks()) do
        local extra = task._extra or {}
        local sid = extra['_s3_sync_id']
        if sid then
          local_by_sync_id[sid] = task
        end
      end

      for _, remote_task in ipairs(s_remote:tasks()) do
        local r_extra = remote_task._extra or {}
        local r_sid = r_extra['_s3_sync_id']
        if not r_sid then
          goto continue
        end

        local local_task = local_by_sync_id[r_sid]
        if local_task then
          local r_mod = remote_task.modified or ''
          local l_mod = local_task.modified or ''
          if r_mod > l_mod then
            local_task.description = remote_task.description
            local_task.status = remote_task.status
            local_task.category = remote_task.category
            local_task.priority = remote_task.priority
            local_task.due = remote_task.due
            local_task.recur = remote_task.recur
            local_task.recur_mode = remote_task.recur_mode
            local_task['end'] = remote_task['end']
            local_task._extra = local_task._extra or {}
            local_task._extra['_s3_sync_id'] = r_sid
            local_task.modified = remote_task.modified
            updated = updated + 1
          else
            unchanged = unchanged + 1
          end
        else
          s:add({
            description = remote_task.description,
            status = remote_task.status,
            category = remote_task.category,
            priority = remote_task.priority,
            due = remote_task.due,
            recur = remote_task.recur,
            recur_mode = remote_task.recur_mode,
            _extra = { _s3_sync_id = r_sid },
          })
          created = created + 1
        end

        ::continue::
      end

      os.remove(tmpfile)
      util.finish(s)
      log.info('s3 pull: ' .. util.fmt_counts({
        { created, 'added' },
        { updated, 'updated' },
        { unchanged, 'unchanged' },
      }))
    end)
  end)
end

function M.sync()
  util.async(function()
    util.with_guard('s3', function()
      local s3cfg = get_config()
      if not s3cfg or not s3cfg.bucket then
        log.error('s3: bucket is required. Set sync.s3.bucket in config.')
        return
      end
      local key = s3cfg.key or 'pending.json'
      local tmpfile = vim.fn.tempname() .. '.json'

      local cmd = base_cmd()
      vim.list_extend(cmd, { 's3', 'cp', 's3://' .. s3cfg.bucket .. '/' .. key, tmpfile })
      local result = util.system(cmd, { text = true })

      local s = require('pending').store()
      local created, updated = 0, 0

      if result.code == 0 then
        local store = require('pending.store')
        local s_remote = store.new(tmpfile)
        local load_ok = pcall(function()
          s_remote:load()
        end)

        if load_ok then
          local local_by_sync_id = {}
          for _, task in ipairs(s:tasks()) do
            local extra = task._extra or {}
            local sid = extra['_s3_sync_id']
            if sid then
              local_by_sync_id[sid] = task
            end
          end

          for _, remote_task in ipairs(s_remote:tasks()) do
            local r_extra = remote_task._extra or {}
            local r_sid = r_extra['_s3_sync_id']
            if not r_sid then
              goto continue
            end

            local local_task = local_by_sync_id[r_sid]
            if local_task then
              local r_mod = remote_task.modified or ''
              local l_mod = local_task.modified or ''
              if r_mod > l_mod then
                local_task.description = remote_task.description
                local_task.status = remote_task.status
                local_task.category = remote_task.category
                local_task.priority = remote_task.priority
                local_task.due = remote_task.due
                local_task.recur = remote_task.recur
                local_task.recur_mode = remote_task.recur_mode
                local_task['end'] = remote_task['end']
                local_task._extra = local_task._extra or {}
                local_task._extra['_s3_sync_id'] = r_sid
                local_task.modified = remote_task.modified
                updated = updated + 1
              end
            else
              s:add({
                description = remote_task.description,
                status = remote_task.status,
                category = remote_task.category,
                priority = remote_task.priority,
                due = remote_task.due,
                recur = remote_task.recur,
                recur_mode = remote_task.recur_mode,
                _extra = { _s3_sync_id = r_sid },
              })
              created = created + 1
            end

            ::continue::
          end
        end
      end
      os.remove(tmpfile)

      for _, task in ipairs(s:tasks()) do
        ensure_sync_id(task)
      end
      s:save()

      local f = io.open(s.path, 'r')
      if not f then
        log.error('s3 sync: failed to read store file')
        return
      end
      local content = f:read('*a')
      f:close()

      local push_tmpfile = vim.fn.tempname() .. '.json'
      local tf = io.open(push_tmpfile, 'w')
      if not tf then
        log.error('s3 sync: failed to create temp file')
        return
      end
      tf:write(content)
      tf:close()

      local push_cmd = base_cmd()
      vim.list_extend(push_cmd, { 's3', 'cp', push_tmpfile, 's3://' .. s3cfg.bucket .. '/' .. key })
      local push_result = util.system(push_cmd, { text = true })
      os.remove(push_tmpfile)

      if push_result.code ~= 0 then
        log.error('s3 sync push: ' .. (push_result.stderr or 'unknown error'))
        util.finish(s)
        return
      end

      util.finish(s)
      log.info('s3 sync: pull ' .. util.fmt_counts({
        { created, 'added' },
        { updated, 'updated' },
      }) .. ' | push uploaded')
    end)
  end)
end

---@return nil
function M.health()
  if vim.fn.executable('aws') == 1 then
    vim.health.ok('aws CLI found')
  else
    vim.health.error('aws CLI not found (required for S3 sync)')
  end

  local s3cfg = get_config()
  if s3cfg and s3cfg.bucket then
    vim.health.ok('S3 bucket configured: ' .. s3cfg.bucket)
  else
    vim.health.warn('S3 bucket not configured — set sync.s3.bucket')
  end
end

M._ensure_sync_id = ensure_sync_id

return M