local adapter = {}

adapter.name = "agentrouter"
adapter.version = "1.0.0"
adapter.endpoint = "/chat/completions"
adapter.headers = {}

-- AgentRouter 的阿里云 WAF 按三重维度校验：出口 IP（必须海外）、
-- TLS 指纹（JS/Go HTTP 层与 curl 不同）、浏览器指纹 header 集。
-- 纯 UA 已不够：WAF 拦 12 种 agent CLI UA 中的 10 种（全 405 HTML），
-- 只有同时带 Origin: qwen.ai + Referer + X-Requested-With 才放行，
-- 且同 IP 短时间连续 3+ 次请求会被速率封禁，靠 adapter 侧低频调用 +
-- llmsproxy 的 prefFailStep 冷却自然限制，来源无法控制速率。
local default_ua = "QwenCode/0.2.0 (linux; x64)"

-- AgentRouter fronts Claude models (claude-opus-4-8), and Claude upstreams
-- enforce Anthropic's tool id rule ^[a-zA-Z0-9_-]{1,64}$ by rejecting the WHOLE
-- request. Plain OpenAI does not, so an id minted by a permissive model (e.g.
-- "bash:0" from moonshotai/kimi-k3) is replayed here by the client and kills
-- every turn. See anthropic.lua / openai.lua for the same helper: Lua adapters
-- have no shared prelude, so each carries its own copy.
local TOOL_ID_MAX = 64

local function safe_tool_id(id)
    if type(id) ~= "string" or id == "" then return id end
    local clean = string.gsub(id, "[^A-Za-z0-9_-]", "_")
    if clean == id and #clean <= TOOL_ID_MAX then
        return clean
    end
    local digest = string.sub(sha256_hex(id), 1, 8)
    local keep = TOOL_ID_MAX - #digest - 1
    if #clean > keep then clean = string.sub(clean, 1, keep) end
    return clean .. "_" .. digest
end

function adapter.transform_request(raw_body)
    local ok, req = pcall(json.decode, raw_body)
    if not ok then return raw_body end
    req.disable_thinking = nil
    req.extra_body = nil
    if req.messages then
        for _, msg in ipairs(req.messages) do
            msg.reasoning_content = nil
            if msg.tool_call_id ~= nil then
                msg.tool_call_id = safe_tool_id(msg.tool_call_id)
            end
            if type(msg.tool_calls) == "table" then
                for _, tc in ipairs(msg.tool_calls) do
                    if type(tc) == "table" and tc.id ~= nil then
                        tc.id = safe_tool_id(tc.id)
                    end
                end
            end
        end
    end
    return json.encode(req)
end

-- 注入 Authorization + 官方客户端 User-Agent
function adapter.build_headers(meta)
    local ua = default_ua
    local meta_ua = (meta.source or {}).meta and (meta.source).meta.user_agent
    if meta_ua and meta_ua ~= "" then
        ua = meta_ua
    end
    return {
        ["Content-Type"] = "application/json",
        ["Authorization"] = "Bearer " .. meta.api_key,
        ["User-Agent"] = ua,
        -- QwenCode client fingerprint: WAF rejects bare UA without these.
        ["Accept"] = "application/json, text/plain, */*",
        ["Accept-Language"] = "zh-CN,zh;q=0.9",
        ["Origin"] = "https://qwen.ai",
        ["Referer"] = "https://qwen.ai/",
        ["X-Requested-With"] = "XMLHttpRequest",
        ["Connection"] = "keep-alive",
    }
end

function adapter.transform_response(raw_body)
    local ok, resp = pcall(json.decode, raw_body)
    if not ok or resp == nil then return raw_body end

    local unified = {
        content = "",
        finish_reason = "",
        token_usage = { prompt = 0, completion = 0, total = 0 }
    }

    if type(resp.usage) == "table" then
        unified.token_usage.prompt = resp.usage.prompt_tokens or 0
        unified.token_usage.completion = resp.usage.completion_tokens or 0
        unified.token_usage.total = resp.usage.total_tokens or 0
        local hit = 0
        if type(resp.usage.prompt_tokens_details) == "table" and resp.usage.prompt_tokens_details.cached_tokens ~= nil then
            hit = resp.usage.prompt_tokens_details.cached_tokens
            unified.token_usage.prompt_tokens_details = { cached_tokens = hit }
        end
        if (resp.usage.prompt_cache_hit_tokens or 0) > 0 then
            unified.token_usage.prompt_cache_hit_tokens = resp.usage.prompt_cache_hit_tokens
            unified.token_usage.prompt_cache_miss_tokens = resp.usage.prompt_cache_miss_tokens or 0
            if hit == 0 then
                unified.token_usage.prompt_tokens_details = { cached_tokens = resp.usage.prompt_cache_hit_tokens }
            end
        end
    end

    if type(resp.choices) == "table" and #resp.choices > 0 then
        local ch = resp.choices[1]
        if type(ch.message) == "table" then
            unified.content = ch.message.content or ""
            if ch.message.reasoning_content then
                unified.reasoning_content = ch.message.reasoning_content
            end
            if type(ch.message.tool_calls) == "table" then
                local tcs = {}
                for _, tc in ipairs(ch.message.tool_calls) do
                    local args_ok, args = pcall(json.decode, tc["function"].arguments)
                    if not args_ok then args = {} end
                    table.insert(tcs, {
                        id = safe_tool_id(tc.id),
                        type = tc.type or "function",
                        name = tc["function"].name,
                        arguments = args
                    })
                end
                unified.tool_calls = tcs
            end
        end
        unified.finish_reason = ch.finish_reason or ""
    end

    return json.encode(unified)
end

function adapter.transform_stream_chunk(raw_chunk)
    local ok, chunk = pcall(json.decode, raw_chunk)
    if not ok then return "" end

    -- usage-only terminal chunk (empty choices + usage): forward it so the
    -- gateway emits exact token counts (and cache fields when present).
    local uses = nil
    if type(chunk.usage) == "table" then
        uses = {
            prompt = chunk.usage.prompt_tokens or chunk.usage.prompt or 0,
            completion = chunk.usage.completion_tokens or chunk.usage.completion or 0,
            total = chunk.usage.total_tokens or chunk.usage.total or 0,
        }
        if type(chunk.usage.prompt_tokens_details) == "table" and chunk.usage.prompt_tokens_details.cached_tokens ~= nil then
            uses.prompt_tokens_details = { cached_tokens = chunk.usage.prompt_tokens_details.cached_tokens }
        elseif (chunk.usage.prompt_cache_hit_tokens or 0) > 0 then
            uses.prompt_cache_hit_tokens = chunk.usage.prompt_cache_hit_tokens
            uses.prompt_cache_miss_tokens = chunk.usage.prompt_cache_miss_tokens or 0
            uses.prompt_tokens_details = { cached_tokens = chunk.usage.prompt_cache_hit_tokens }
        end
    end

    if not chunk.choices or #chunk.choices == 0 then
        if uses ~= nil then
            return json.encode({ usage = uses, done = false })
        end
        return ""
    end
    local delta = chunk.choices[1].delta or {}
    local fr = chunk.choices[1].finish_reason

    local finish = (type(fr) == "string" and fr ~= "") and fr or nil

    local unified = {
        content = delta.content or "",
        done = (finish ~= nil)
    }
    if finish then
        unified.finish_reason = finish
    end
    if delta.reasoning_content then
        unified.reasoning_content = delta.reasoning_content
    end
    if delta.tool_calls then
        -- Sanitize outbound too: a dirty id must never enter a client session,
        -- because the client replays it to every other source. Only the first
        -- fragment of a streamed call carries an id; later argument fragments
        -- have none and must stay id-less for index-based accumulation.
        for _, tc in ipairs(delta.tool_calls) do
            if type(tc) == "table" and tc.id ~= nil then
                tc.id = safe_tool_id(tc.id)
            end
        end
        unified.tool_calls = delta.tool_calls
    end
    if uses ~= nil then
        unified.usage = uses
    end
    return json.encode(unified)
end

-- 错误收敛：前置 WAF 会返回整页 HTML（阿里云盾），JSON 时为 new-api 风格
function adapter.transform_error(status, body)
    local low = string.lower(body or "")
    if string.sub(low, 1, 9) == "<!doctype" or string.find(low, "<html", 1, true) then
        return "blocked by AgentRouter WAF"
    end
    local ok, resp = pcall(json.decode, body)
    if not ok or type(resp) ~= "table" then return nil end
    local e = resp.error
    if type(e) == "table" and type(e.message) == "string" then
        return e.message
    end
    return nil
end

return adapter