local path = require 'pandoc.path'
local utils = require 'pandoc.utils'
local common = require 'scripts.lib.common'
local sort = require 'scripts.lib.sort'

function slug(str)
    return str:lower():gsub("[^ a-z]", ""):gsub("[ ]+", "-")
end

function format_date(date)
    if not date then return date end

    date = pandoc.utils.normalize_date(utils.stringify(date))
    local year, month, day = date:match("(%d%d%d%d)-(%d%d)-(%d%d)")
    if not year then return nil end

    local time = os.time({ year = tonumber(year), month = tonumber(month), day = tonumber(day) })
    return {
        yyyy_mm_dd = os.date("%F", time),
        yyyy = os.date("%Y", time),
        mm = os.date("%m", time),
        dd = os.date("%d", time),
        rfc3339 = os.date("%FT%T+00:00", time),
        long = os.date("%B %d, %Y", time),
        short = os.date("%b %d, %Y", time),
    }
end

function make_absolute(rel, base)
    return path.is_absolute(rel) and rel or path.join({ path.directory(base), rel })
end

function resolve_layout(depth)
    local layout = "categorized_list"

    if depth == 0 then
        layout = "page"
    elseif depth == 1 then
        layout = "list"
    end

    return layout
end

function prep_namespace(namespace)
    namespace = utils.stringify(namespace)

    local root = "index"
    if namespace ~= "" then root = namespace:gsub("^/([^/]*).*$", "%1") end

    return { root = { id = root, ["is_" .. root] = true }, full = namespace }
end

function prep_menu(active_id, main_menu)
    local active_item = nil
    local items = pandoc.List()

    for i = 1, #main_menu do
        local item = main_menu[i]
        local active = utils.stringify(item.id) == active_id
        item.active = active
        if active then active_item = item end
        if not item.hidden or item.active then items:insert(item) end
    end

    return { items = items, active = active_item }
end

function process_pages(meta)
    local pages_all = pandoc.List()
    local pages_date_desc = pandoc.List()

    for id, p in pairs(meta.pages) do
        if not p.unlisted then
            pages_all:insert(id)
            if p.last_update then pages_date_desc:insert(id) end
        end
    end

    pages_all:sort(sort.page_sort(meta.list_order, meta.pages))
    pages_date_desc:sort(sort.page_sort("date_desc", meta.pages))

    meta.pages = {
        all = pages_all,
        date_desc = pages_date_desc,
        by_id = meta.pages
    }
end

function find_depth(meta)
    if meta.depth then
        meta.depth = tonumber(meta.depth)
    end

    local depth = 0

    for _, p in pairs(meta.pages) do
        find_depth(p)
        if not p.unlisted then
            local d = p.depth + 1
            if d > depth then depth = d end
        end
    end

    meta.depth = depth
end

function resolve_dates(meta)
    if meta.last_update then
        meta.last_update = format_date(meta.last_update)
    elseif #meta.pages.date_desc ~= 0 then
        meta.last_update = meta.pages.by_id[meta.pages.date_desc[1]].last_update
    elseif meta.date then
        meta.last_update = format_date(meta.date)
    end

    if meta.date then
        meta.date = format_date(meta.date)
    elseif meta.last_update then
        meta.date = meta.last_update
    end

    meta.was_updated = meta.date and meta.last_update and meta.date.yyyy_mm_dd ~= meta.last_update.yyyy_mm_dd
end

function process_base(build, meta)
    meta.namespace = prep_namespace(meta.namespace)
    meta.id = meta.namespace.full:gsub("^.*/(.-)$", "%1")
    meta.file_out = utils.stringify(meta.file_out)
    meta.unlisted = meta.unlisted or (meta.draft and build.mode ~= "dev")
    meta.redirect = meta.url and true
    meta.url = meta.url or meta.file_out
    meta.title = meta.title and utils.stringify(meta.title) or ""
    meta.slug = slug(meta.title)
    meta.schema_type = meta.schema_type or "CreativeWork"
    meta.list_layout = common.prep_layout(meta.list_layout or "list")
    meta.list_order = meta.list_order and utils.stringify(meta.list_order)
    meta.position = meta.position and tonumber(utils.stringify(meta.position))
    meta.thumbnail = meta.thumbnail and make_absolute("thumbnail." .. utils.stringify(meta.thumbnail), meta.file_out)
    meta.layout = common.prep_layout(meta.layout or (meta.redirect and "redirect") or resolve_layout(meta.depth))

    meta.show_date = meta.parent and meta.parent.list_order == "date_desc"
    meta.category = meta.parent and meta.parent.title
    meta.icon = meta.icon or (meta.parent and meta.parent.icon)
    meta.post_icon = meta.post_icon or (meta.parent and meta.parent.list_post_icon) or
        (meta.parent and meta.parent.parent and meta.parent.parent.list_post_icon)
    meta.indicator = meta.parent and meta.parent.list_read_indicators

    meta.content = meta.content:filter(function (el)
        return el.tag ~= "LineBreak"
    end)
end

function process(global, build, meta)
    process_base(build, meta)

    for _, p in pairs(meta.pages) do
        p.parent = meta
        process(global, build, p)
        p.parent = nil
    end

    process_pages(meta)
    resolve_dates(meta)
end

function find_pos(meta)
    for _, p in pairs(meta.pages.by_id) do
        p.parent = meta
        find_pos(p)
        p.parent = nil
    end

    if not meta.parent then return end

    local pages = meta.parent.list_order == "date_desc" and meta.parent.pages.date_desc or meta.parent.pages.all
    local _, index = pages:find(meta.id)

    if index == nil then return end

    meta.prev = index <= #pages - 1 and pages[index + 1] or nil
    meta.next = index >= 2 and pages[index - 1] or nil
end

function Meta(meta)
    local build = {}

    for key, value in pairs(meta) do
        local suffix = key:match('^build.(.*)$')

        if suffix then
            build[suffix] = value
            meta[key] = nil
        end
    end

    meta.site.url = utils.stringify(meta.site.url):gsub("/$", "")

    find_depth(meta)
    process(meta, build, meta)
    find_pos(meta)

    return meta
end