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)
    site_url = utils.stringify(site_url)
    ref_file = utils.stringify(ref_file)
    target_file = utils.stringify(target_file):gsub("/index%.html$", "/")

    local ref_base_dir = path.directory(ref_file)
    local abs = target_file
    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 process_pages(global, build, meta)
    for _, p in pairs(meta.pages.by_id) do
        process_pages(global, build, p)
    end

    meta.pages = {
        all = meta.pages.all:map(utils.stringify):map(function (ref) return meta.pages.by_id[ref] end),
        date_desc = meta.pages.date_desc:map(utils.stringify):map(function (ref) return meta.pages.by_id[ref] end),
        by_id = meta.pages.by_id
    }
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 d1_page_to_list_item(meta, p)
    return {
        title = p.title,
        subtitle = p.subtitle,
        date = p.date,
        last_update = p.last_update,
        show_date = meta.list_order == "date_desc",
        schema_type = p.schema_type,
        draft = p.draft,
        position = p.position,
        url = p.url,
        rel = p.rel,
        slug = p.slug,
        thumbnail = p.thumbnail,
        icon = p.icon or meta.icon,
        post_icon = p.post_icon or meta.list_post_icon,
        indicator = meta.list_read_indicators,
    }
end

function d2_page_to_list_item(meta, cat, p, set_cat_title)
    return {
        title = p.title,
        subtitle = p.subtitle,
        category = set_cat_title and cat.title,
        date = p.date,
        last_update = p.last_update,
        show_date = cat.list_order == "date_desc",
        schema_type = p.schema_type,
        draft = p.draft,
        position = p.position,
        url = p.url,
        rel = p.rel,
        slug = p.slug,
        thumbnail = p.thumbnail,
        icon = p.icon or cat.icon,
        post_icon = p.post_icon or cat.list_post_icon or meta.list_post_icon,
        indicator = cat.list_read_indicators,
    }
end

function cat_to_list_cat(cat, allItems)
    local limit = cat.list_limit or 9999
    local items = allItems:take(limit)
    local omitted = #allItems - #items

    return {
        title = cat.title,
        description = (cat.description and pandoc.MetaBlocks(pandoc.Para(cat.description))) or
            (not cat.no_description and cat.content),
        last_update = cat.last_update,
        schema_type = cat.schema_type,
        url = cat.url,
        slug = cat.slug,
        layout = cat.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(meta, 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(meta, cat, p, 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(cat, c, p, true) end)
                    else
                        return pandoc.List({ d1_page_to_list_item(cat, 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 process_base(meta)
    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)
end

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

    for _, p in pairs(meta.pages.by_id) do
        process(global, build, p)
    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
    }

    meta = meta.tree

    process(global, build, meta)

    local parts = utils.stringify(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_pages(global, build, meta)

    meta.list = generate_list(meta)

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

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

    meta.build = build

    return meta
end