local json = require("json")
local json_util = require("json.util")

-- Recursively replace LuaJSON's truthy null-sentinel functions with nil
-- (JSON null), so server payloads behave like normal Lua tables.
local function strip_json_nulls(t)
    for k, v in pairs(t) do
        if type(v) == "function" then
            t[k] = nil
        elseif type(v) == "table" then
            strip_json_nulls(v)
        end
    end
    return t
end
local logger = require("logger")
local ltn12 = require("ltn12")
local socketutil = require("socketutil")

local http = require("socket.http")
local ssl_ok, ssl_https = pcall(require, "ssl.https")

local PROGRESS_TIMEOUTS = { 2, 5 }
local AUTH_TIMEOUTS = { 5, 10 }

local BookhoardAPI = {
    server_url = nil,
    auth_token = nil,
}

function BookhoardAPI:new(o)
    o = o or {}
    setmetatable(o, self)
    self.__index = self
    return o
end

function BookhoardAPI:_buildHeaders()
    local headers = {
        ["Content-Type"] = "application/json",
        ["Accept"] = "application/json",
    }
    if self.auth_token then
        headers["Authorization"] = "Bearer " .. self.auth_token
    end
    return headers
end

function BookhoardAPI:_request(method, path, body, timeouts)
    if not self.server_url then
        return false, { error = "server URL not configured" }
    end

    local url = self.server_url .. path
    local sink = {}
    local headers = self:_buildHeaders()
    local body_str = body and json.encode(body) or nil

    if body_str then
        headers["Content-Length"] = tostring(#body_str)
    end

    local request = {
        url = url,
        method = method,
        headers = headers,
        sink = ltn12.sink.table(sink),
    }

    if body_str then
        request.source = ltn12.source.string(body_str)
    end

    socketutil:set_timeout(timeouts[1], timeouts[2])

    local ok, err, code
    if url:match("^https://") then
        if ssl_ok then
            ok, err, code = pcall(ssl_https.request, request)
        else
            socketutil:reset_timeout()
            return false, { error = "HTTPS not supported on this device" }
        end
    else
        ok, err, code = pcall(http.request, request)
    end

    socketutil:reset_timeout()

    if not ok then
        logger.warn("BookhoardAPI: request failed:", err)
        return false, { error = tostring(err) }
    end

    local response_body = table.concat(sink)
    local status = tonumber(code)

    if status and status >= 200 and status < 300 then
        if response_body and #response_body > 0 then
            local decode_ok, data = pcall(json.decode, response_body)
            if decode_ok and type(data) == "table" then
                -- LuaJSON decodes JSON null into a truthy sentinel FUNCTION,
                -- which defeats every `if not x.field` nil-check downstream
                -- (crash: "attempt to index local 'progress' (a function
                -- value)"). Normalize sentinels to nil at the boundary.
                strip_json_nulls(data)
                return true, data
            end
            return true, response_body
        end
        return true, nil
    end

    local error_msg = "HTTP " .. tostring(code)
    if response_body and #response_body > 0 then
        local decode_ok, data = pcall(json.decode, response_body)
        if decode_ok and data and data.error then
            error_msg = data.error
        end
    end
    logger.warn("BookhoardAPI:", method, path, "→", status, error_msg)
    return false, { status = status, error = error_msg }
end

function BookhoardAPI:registerDevice(device_name, device_identifier)
    return self:_request("POST", "/api/devices/register", {
        device_name = device_name,
        device_type = "koreader",
        device_identifier = device_identifier,
    }, AUTH_TIMEOUTS)
end

function BookhoardAPI:checkRegistrationStatus(registration_id)
    return self:_request("POST", "/api/devices/register/status", {
        registration_id = registration_id,
    }, AUTH_TIMEOUTS)
end

function BookhoardAPI:syncProgress(book_data, sync_mode)
    local books = json_util.InitArray({ book_data })
    return self:_request("POST", "/api/sync/koreader/progress", {
        books = books,
        sync_mode = sync_mode or "immediate",
    }, PROGRESS_TIMEOUTS)
end

-- Read-only SHA-256 → book UUID lookup. Used to link a freshly downloaded
-- book WITHOUT pushing progress (a push would transmit the device's
-- first-page position and clobber/conflict with real server progress).
function BookhoardAPI:resolveBook(sha256)
    return self:_request("GET", "/api/sync/koreader/resolve?sha256=" .. sha256, nil, PROGRESS_TIMEOUTS)
end

function BookhoardAPI:getMetadata(uuid)
    return self:_request("GET", "/api/sync/koreader/metadata/" .. uuid, nil, PROGRESS_TIMEOUTS)
end

-- ----- Ratings / review / reading-time bridge (handoff item 4 Batch B) -----

-- GET ref: only uuid/sha256 travel as query params (both URL-safe); the
-- fallback title/authors resolution only exists on the push side, where the
-- body can carry them. An unlinked book has no server rating to pull anyway.
local function book_ref_query(ref)
    local q = {}
    if ref.uuid and ref.uuid ~= "" then
        table.insert(q, "uuid=" .. ref.uuid)
    end
    if ref.sha256 and ref.sha256 ~= "" then
        table.insert(q, "sha256=" .. ref.sha256)
    end
    return table.concat(q, "&")
end

local function book_ref_body(ref)
    local authors = ref.authors or {}
    json_util.InitArray(authors)
    return {
        uuid = ref.uuid,
        sha256 = ref.sha256,
        title = ref.title,
        authors = authors,
    }
end

-- Server rating is 1-10; koreader's summary.rating is 0-5 (0 = unrated).
function BookhoardAPI:getRating(ref)
    return self:_request("GET", "/api/sync/koreader/rating?" .. book_ref_query(ref), nil, PROGRESS_TIMEOUTS)
end

function BookhoardAPI:setRating(ref, rating)
    local body = book_ref_body(ref)
    body.rating = rating
    return self:_request("POST", "/api/sync/koreader/rating", body, PROGRESS_TIMEOUTS)
end

-- Review bodies are RAW MARKDOWN both ways (koreader's review box shows it
-- literally — the same accepted tradeoff as notes).
function BookhoardAPI:getReview(ref)
    return self:_request("GET", "/api/sync/koreader/review?" .. book_ref_query(ref), nil, PROGRESS_TIMEOUTS)
end

function BookhoardAPI:setReview(ref, review)
    local body = book_ref_body(ref)
    body.review = review
    return self:_request("POST", "/api/sync/koreader/review", body, PROGRESS_TIMEOUTS)
end

-- Cumulative total reading seconds for the book; the server converts
-- watermark-deltas into reading_history sessions (device-attributed).
function BookhoardAPI:pushStats(ref, total_seconds)
    local body = book_ref_body(ref)
    body.total_seconds = math.floor(total_seconds)
    return self:_request("POST", "/api/sync/koreader/stats", body, PROGRESS_TIMEOUTS)
end



return BookhoardAPI