local mp = require 'mp'
local msg = require 'mp.msg'
local utils = require 'mp.utils'

local o = require 'modules.options'
local g = require 'modules.globals'
local ass = require 'modules.ass'
local scanning = require 'modules.navigation.scanning'
local fb_utils = require 'modules.utils'
local cursor = require 'modules.navigation.cursor'

---@class directory_movement
local directory_movement = {}
local NavType = scanning.NavType

---Appends an item to the directory stack, wiping any
---directories further ahead than the current position.
---@param dir string
local function directory_stack_append(dir)
    -- don't clear the stack if we're re-entering the same directory
    if g.directory_stack.stack[g.directory_stack.position + 1] == dir then
        g.directory_stack.position = g.directory_stack.position + 1
        return
    end

    local j = #g.directory_stack.stack
    while g.directory_stack.position < j do
        g.directory_stack.stack[j] = nil
        j = j - 1
    end
    table.insert(g.directory_stack.stack, dir)
    g.directory_stack.position = g.directory_stack.position + 1
end

---@param dir string
local function directory_stack_prepend(dir)
    table.insert(g.directory_stack.stack, 1, dir)
    g.directory_stack.position = 1
end

---Clears directories from the history
---@param from? number All entries >= this index are cleared.
---@return string[]
function directory_movement.clear_history(from)
    ---@type string[]
    local cleared = {}

    from = from or 1
    for i = g.history.size, from, -1 do
        table.insert(cleared, g.history.list[i])
        g.history.list[i] = nil
        g.history.size = g.history.size - 1

        if g.history.position >= i then
            g.history.position = g.history.position - 1
        end
    end

    return cleared
end

---Append a directory to the history
---If we have navigated backward in the history,
---then clear any history beyond the current point.
---@param directory string
function directory_movement.append_history(directory)
    if g.history.list[g.history.position] == directory then
        msg.debug('reloading same directory - history unchanged:', directory)
        return
    end

    msg.debug('appending to history:', directory)
    if g.history.position < g.history.size then
        directory_movement.clear_history(g.history.position + 1)
    end

    table.insert(g.history.list, directory)
    g.history.size = g.history.size + 1
    g.history.position = g.history.position + 1

    if g.history.size > o.history_size then
        table.remove(g.history.list, 1)
        g.history.size = g.history.size - 1
    end
end

---@param filepath string
function directory_movement.set_current_file(filepath)
    --if we're in idle mode then we want to open the working directory
    if filepath == nil then
        g.current_file.directory = fb_utils.fix_path( mp.get_property("working-directory", ""), true)
        g.current_file.name = nil
        g.current_file.path = nil
        g.current_file.original_path = nil
        return
    end

    local absolute_path = fb_utils.absolute_path(filepath)
    local resolved_path = fb_utils.resolve_directory_mapping(absolute_path)

    g.current_file.directory, g.current_file.name = utils.split_path(resolved_path)
    g.current_file.original_path = absolute_path
    g.current_file.path = resolved_path

    if o.cursor_follows_playing_item then cursor.select_playing_item() end
    ass.update_ass()
end

--the base function for moving to a directory
---@param directory string
---@param nav_type? NavigationType
---@param store_history? boolean default `true`
---@param parse_properties? ParseProperties
---@return thread
function directory_movement.goto_directory(directory, nav_type, store_history, parse_properties)
    local current = g.state.list[g.state.selected]
    g.state.directory = directory

    if g.state.directory_label then
        if nav_type == NavType.DOWN then
            g.state.directory_label = g.state.directory_label..(current.label or current.name)
        elseif nav_type == NavType.UP then
            g.state.directory_label = string.match(g.state.directory_label, "^(.-/+)[^/]+/*$")
        end
    end

    if o.history_size > 0 and store_history == nil or store_history then
        directory_movement.append_history(directory)
    end

    return scanning.rescan(nav_type or NavType.GOTO, nil, parse_properties)
end

---Move the browser to a particular point in the browser history.
---The history is a linear list of visited directories from oldest to newest.
---If the user changes directories while the current history position is not the head of the list,
---any later directories get cleared and the new directory becomes the new head.
---@param pos number The history index to move to. Clamped to [1,history_length]
---@return number|false # The index actually moved to after clamping. Returns -1 if the index was invalid (can occur if history is empty or disabled)
function directory_movement.goto_history(pos)
    if type(pos) ~= "number" then return false end

    if pos < 1 then pos = 1
    elseif pos > g.history.size then pos = g.history.size end
    if not g.history.list[pos] then return false end

    g.history.position = pos
    directory_movement.goto_directory(g.history.list[pos])
    return pos
end

--loads the root list
function directory_movement.goto_root()
    msg.verbose('jumping to root')
    return directory_movement.goto_directory("")
end

--switches to the directory of the currently playing file
function directory_movement.goto_current_dir()
    msg.verbose('jumping to current directory')
    return directory_movement.goto_directory(g.current_file.directory)
end

--moves up a directory
function directory_movement.up_dir()
    if g.state.directory == '' then return end

    local cached_parent_dir = g.directory_stack.stack[g.directory_stack.position - 1]
    if cached_parent_dir then
        g.directory_stack.position = g.directory_stack.position - 1
        return directory_movement.goto_directory(cached_parent_dir, NavType.UP)
    end

    local parent_dir = g.state.directory:match("^(.-/+)[^/]+/*$") or ""

    if o.skip_protocol_schemes and parent_dir:find("^(%a[%w+-.]*)://$") then
        return directory_movement.goto_root()
    end

    directory_stack_prepend(parent_dir)
    return directory_movement.goto_directory(parent_dir, NavType.UP)
end

--moves down a directory
function directory_movement.down_dir()
    local current = g.state.list[g.state.selected]
    if not current or not fb_utils.parseable_item(current) then return end

    local directory, redirected = fb_utils.get_new_directory(current, g.state.directory)
    directory_stack_append(directory)
    return directory_movement.goto_directory(directory, redirected and NavType.REDIRECT or NavType.DOWN)
end

--moves backwards through the directory history
function directory_movement.back_history()
    msg.debug('moving backwards in history to', g.history.list[g.history.position-1])
    if g.history.position == 1 then return end
    directory_movement.goto_history(g.history.position - 1)
end

--moves forward through the history
function directory_movement.forwards_history()
    msg.debug('moving forwards in history to', g.history.list[g.history.position+1])
    if g.history.position == g.history.size then return end
    directory_movement.goto_history(g.history.position + 1)
end

return directory_movement