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

function resolve_url(site_url, ref_file, target_file)
    local ref_base_dir = path.directory(ref_file)
    local abs = target_file:gsub("/index%.html$", "/")
    local rel = path.make_relative(abs, ref_base_dir, true)
    local full = (abs:sub(1, 1) == "/" and (site_url .. abs)) or abs

    return { abs = abs, rel = rel, full = full }
end

function prep_menu(namespace, main_menu)
    namespace = utils.stringify(namespace)

    local active_item = nil
    local items = pandoc.List()

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

    return { items = items, active = active_item }
end

function d1_page_to_list_item(meta)
    return {
        title = meta.title,
        subtitle = meta.subtitle,
        date = meta.date,
        last_update = meta.last_update,
        show_date = meta.show_date,
        schema_type = meta.schema_type,
        draft = meta.draft,
        position = meta.position,
        url = meta.url,
        rel = meta.rel,
        slug = meta.slug,
        thumbnail = meta.thumbnail,
        icon = meta.icon,
        post_icon = meta.post_icon,
        indicator = meta.indicator,
    }
end

function d2_page_to_list_item(meta, unlisted, with_category)
    return {
        title = meta.title,
        subtitle = meta.subtitle,
        category = with_category and meta.category,
        date = meta.date,
        last_update = meta.last_update,
        show_date = meta.show_date,
        schema_type = meta.schema_type,
        draft = meta.draft,
        position = meta.position,
        url = meta.url,
        rel = meta.rel,
        slug = meta.slug,
        thumbnail = meta.thumbnail,
        icon = meta.icon,
        post_icon = meta.post_icon,
        indicator = meta.indicator,
        unlisted = unlisted
    }
end

function cat_to_list_cat(meta, allItems)
    local limit = meta.list_limit or 9999
    local items = allItems:filter(function (item) return not item.unlisted end):take(limit)
    local omitted = #allItems - #items

    local description = nil

    if meta.description then
        description = pandoc.Para(meta.description)
    elseif not meta.no_description then
        description = meta.content
    end

    return {
        title = meta.title,
        description = description,
        last_update = meta.last_update,
        schema_type = meta.schema_type,
        url = meta.url,
        slug = meta.slug,
        layout = meta.list_layout,
        items = items,
        total = tostring(#allItems),
        omitted = omitted ~= 0 and tostring(omitted),
    }
end

function generate_list(meta)
    if meta.depth < 1 then return pandoc.List() end

    if meta.depth == 1 then
        return meta.pages.all:map(function (p) return d1_page_to_list_item(p) end)
    end

    if meta.depth == 2 then
        return meta.pages.all
            :map(function(cat)
                local allItems = cat.pages.all:map(function(p) return d2_page_to_list_item(p, false, false) end)

                return cat_to_list_cat(cat, allItems)
            end)
            :filter(function(cat) return #cat.items ~= 0 end)
    end

    if meta.depth == 3 then
        local list = meta.pages.all
            :map(function(cat)
                local allItems = cat.pages.all:flatMap(function(c)
                    if cat.list_flatten and c.depth ~= 0 then
                        return c.pages.all:map(function(p) return d2_page_to_list_item(p, c.list_no_propagate, true) end)
                    else
                        return pandoc.List({ d1_page_to_list_item(c) })
                    end
                end)

                allItems:sort(sort.page_sort(cat.list_order))

                return cat_to_list_cat(cat, allItems)
            end)
            :filter(function(cat) return #cat.items ~= 0 end)

        return list
    end
end

function deref_page(pages)
    return function(ref)
        return pages[utils.stringify(ref)]
    end
end

function generate_related(meta)
    if not meta.parent then return nil end

    local deref = deref_page(meta.parent.pages.by_id)

    meta.prev = meta.prev and d1_page_to_list_item(deref(meta.prev))
    meta.next = meta.next and d1_page_to_list_item(deref(meta.next))

    if meta.prev then meta.prev.is_prev = true end
    if meta.next then meta.next.is_next = true end

    if not meta.prev and not meta.next then return nil end

    local layout
    local layout_id = utils.stringify(meta.parent.list_layout.id)

    if layout_id == "gallery-2" or layout_id == "gallery-3" then
        layout = common.prep_layout("gallery-2")
    else
        layout = common.prep_layout("grid-2")
    end

    return {
        url = meta.parent.url,
        layout = layout,
        prev = meta.prev,
        next = meta.next
    }
end

function process_pages(meta)
    local deref = deref_page(meta.pages.by_id)

    meta.pages.all = meta.pages.all:filterMap(deref)
    meta.pages.date_desc = meta.pages.date_desc:filterMap(deref)
end

function resolve_urls(global, build, meta)
    meta.url = resolve_url(global.site.url, build.file_out, meta.url)

    if meta.feed then
        if meta.file_out:match(".html$") then
            meta.feed = {
                url = resolve_url(global.site.url, build.file_out, meta.file_out:gsub(".html$", ".xml")),
            }
        else
            meta.page = {
                url = resolve_url(global.site.url, build.file_out, meta.file_out:gsub(".xml$", ".html")),
            }
        end
    end

    if meta.thumbnail then
        meta.thumbnail = resolve_url(global.site.url, build.file_out, meta.thumbnail)
    end
end

function process_base(meta)
    meta.id = utils.stringify(meta.id)
    meta.depth = tonumber(utils.stringify(meta.depth))
    meta.file_out = utils.stringify(meta.file_out)
    meta.url = utils.stringify(meta.url)
    meta.title = utils.stringify(meta.title)
    meta.list_limit = meta.list_limit and tonumber(utils.stringify(meta.list_limit))
    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 utils.stringify(meta.thumbnail)
    meta.prev = meta.prev and utils.stringify(meta.prev)
    meta.next = meta.next and utils.stringify(meta.next)
    meta.content = meta.content:filter(function (el)
        return el.tag ~= "LineBreak"
    end)
end

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

    for _, p in pairs(meta.pages.by_id) do
        p.parent = meta
        process(global, build, p, 1)
        p.parent = nil
    end

    process_pages(meta)

    if dir <= 0 and meta.parent then
        process(global, build, meta.parent, -1)
    end
end

function prune_pages(meta, up, down)
    meta.pages.by_id = {}

    if down == 0 then
        meta.pages.all = pandoc.List()
        meta.pages.date_desc = pandoc.List()
    else
        for _, p in pairs(meta.pages.by_id) do
            prune(p, up, down - 1)
        end
    end
end

function prune(meta, up, down)
    prune_pages(meta, up, down)

    if up == 0 then
        meta.parent = nil
    elseif meta.parent then
        prune(meta.parent, up - 1, down)
    end
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

    local global = {
        assets = meta.assets,
        site = meta.site,
        menus = meta.menus
    }

    global.site.url = utils.stringify(global.site.url)

    meta = meta.tree

    local parts = build.namespace:split('/'):skip(1)
    for i = 1, #parts do
        local part = parts[i]
        local p = meta.pages.by_id[part]
        meta.pages.by_id[part] = nil
        p.parent = meta
        meta = p
    end

    process(global, build, meta, 0)

    meta.list = generate_list(meta)
    meta.related = generate_related(meta)

    if global.menus and global.menus.main then
        global.menus.main = prep_menu(meta.namespace.full, global.menus.main)
    end

    prune(meta, 0, 2)

    for key, value in pairs(global) do
        meta[key] = value
    end

    meta.build = build

    return meta
end