-- trae 源适配器（trae-local-api 的 OpenAI 兼容代理）
-- trae-local-api 运行在 http://127.0.0.1:19900，接 Trae CN 账号的云资源。
-- 协议：OpenAI /v1/chat/completions
-- 特性：
--   - 排队：上游 busy 时排队，可能长时间无响应
--   - 非流式请求偶发返回 SSE 数据（upstream bug）
--   - 支持 thinking，由上游模型自动决定是否开启

local adapter = {}
adapter.name = "trae"
adapter.version = "1.0.0"
adapter.endpoint = "/v1/chat/completions"
adapter.headers = {}

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
        end
    end
    return json.encode(req)
end

-- parse_text_tool_calls extracts tool calls that an upstream emitted as PLAIN
-- TEXT instead of using the OpenAI tool_calls field.
--
-- trae-local-api's OpenAI endpoint (/v1/chat/completions) does not read the
-- request's `tools` array at all, so the relayed model is never told the tool
-- schema; it falls back to printing
--     <tool_call>
--     {"name": "get_weather", "arguments": {"location": "北京"}}
--     </tool_call>
-- into message.content, leaves message.tool_calls null, and reports
-- finish_reason="stop". A client following the OpenAI contract therefore never
-- sees a tool call: the agent loop terminates unexpectedly mid-conversation
-- (and a hand-written replay produces an empty function name next turn).
--
-- Both tag spellings are accepted: the same codebase's Anthropic endpoint
-- instructs models to emit <toolcall>, and models mix the two. Key names vary
-- too (arguments / params / input), so all are tried.
--
-- Returns (tool_calls_array_or_nil, content_with_blocks_removed).
local function parse_text_tool_calls(content)
    if type(content) ~= "string" or content == "" then return nil, content end

    local tcs = {}
    local idx = 0

    local function collect(pattern)
        for payload in content:gmatch(pattern) do
            local ok, obj = pcall(json.decode, payload)
            if ok and type(obj) == "table" then
                -- some models wrap it as {"function":{"name":..,"arguments":..}}
                local fn = obj["function"]
                local name = obj.name or (type(fn) == "table" and fn.name) or nil
                if name then
                    local args = obj.arguments or obj.params or obj.input
                    if args == nil and type(fn) == "table" then
                        args = fn.arguments or fn.params
                    end
                    if type(args) == "string" then
                        local aok, decoded = pcall(json.decode, args)
                        args = aok and decoded or {}
                    elseif type(args) ~= "table" then
                        args = {}
                    end
                    idx = idx + 1
                    table.insert(tcs, {
                        id = obj.id or ("call_text_" .. idx),
                        type = "function",
                        name = name,
                        arguments = args
                    })
                end
            end
        end
    end

    -- `<tag ...>` allows attributes; %s* handles the "</tool_call >" spacing
    -- that trae-local-api's own prompt example uses.
    collect("<tool_call[^>]*>%s*(.-)%s*</tool_call%s*>")
    collect("<toolcall[^>]*>%s*(.-)%s*</toolcall%s*>")

    -- Legacy / mimicked form: models that saw past assistant turns folded as
    --   [Called tool: name({...})]
    -- tend to emit the same shape instead of a real  block. Recover it so
    -- the agent loop keeps working; otherwise the client receives plain text
    -- where a structured tool call should be. Capture the name and the JSON
    -- object literal independently (the JSON is the only {...} run here).
    if #tcs == 0 and content:find("%[Called tool") then
        for name, argsraw in content:gmatch("%[Called tool%s*:%s*([%w_%-%.]+)%s*%((%b{})%s*%)%s*%]") do
            local aok, decoded = pcall(json.decode, argsraw)
            idx = idx + 1
            table.insert(tcs, {
                id = "call_legacy_" .. idx,
                type = "function",
                name = name,
                arguments = aok and decoded or {}
            })
        end
    end

    if #tcs == 0 then return nil, content end

    -- drop the blocks from user-visible content; keep any surrounding prose
    local stripped = content:gsub("<tool_call[^>]*>%s*.-%s*</tool_call%s*>", "")
    stripped = stripped:gsub("<toolcall[^>]*>%s*.-%s*</toolcall%s*>", "")
    stripped = stripped:gsub("%[Called tool%s*:%s*[%w_%-%.]+%s*%(%b{}%s*%)%s*%]", "")
    stripped = stripped:gsub("^%s+", ""):gsub("%s+$", "")
    return tcs, stripped
end

function adapter.transform_response(raw_body)
    -- trae-local-api 偶发在非流式请求中返回 SSE 格式数据，
    -- 表现为多个 data: {...} 行或混合了 reasoning_chunk 等。
    -- 剥掉 data: 前缀，取最后一个完整的 JSON 块（通常是
    -- 最终的 stop chunk 或 usage chunk）。
    local use_json = raw_body
    if raw_body:match("^data:") or raw_body:match("\ndata:") then
        -- 取最后一个 data: 行的 JSON
        local last = nil
        for line in raw_body:gmatch("data: ([^\n\r]+)") do
            local trimmed = line:match("^%s*(.-)%s*$")
            if trimmed and trimmed ~= "[DONE]" then
                local ok2, obj = pcall(json.decode, trimmed)
                if ok2 and type(obj) == "table" then
                    last = obj
                end
            end
        end
        if last then
            use_json = json.encode(last)
        end
        -- 如果解析失败，回退到原始 body
    end

    local ok, resp = pcall(json.decode, use_json)
    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
    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" and #ch.message.tool_calls > 0 then
                local tcs = {}
                for _, tc in ipairs(ch.message.tool_calls) do
                    local fn = tc["function"] or {}
                    local args = fn.arguments
                    if type(args) == "string" then
                        local args_ok, decoded = pcall(json.decode, args)
                        args = args_ok and decoded or {}
                    elseif type(args) ~= "table" then
                        args = {}
                    end
                    table.insert(tcs, {
                        id = tc.id,
                        type = tc.type or "function",
                        name = fn.name,
                        arguments = args
                    })
                end
                unified.tool_calls = tcs
            end
        end
        unified.finish_reason = ch.finish_reason or ""

        -- Fallback: trae-local-api's OpenAI endpoint drops the request's
        -- `tools` array entirely, so the relayed model is never told the tool
        -- schema and instead PRINTS a <tool_call>{...}</tool_call> block into
        -- content, leaving message.tool_calls null and finish_reason="stop".
        -- A client following the OpenAI contract then sees a normal completion
        -- and its agent loop terminates mid-conversation. Recover the
        -- structured call so the loop can continue.
        if unified.tool_calls == nil then
            local recovered, cleaned = parse_text_tool_calls(unified.content)
            if recovered then
                unified.tool_calls = recovered
                unified.content = cleaned
                unified.finish_reason = "tool_calls"
            end
        end
    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

    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 uses ~= nil then
        unified.usage = uses
    end
    if delta.reasoning_content then
        unified.reasoning_content = delta.reasoning_content
    end
    if delta.tool_calls then
        unified.tool_calls = delta.tool_calls
    end
    return json.encode(unified)
end

function adapter.transform_error(status, body)
    local ok, resp = pcall(json.decode, body)
    if not ok or type(resp) ~= "table" then
        -- Non-JSON body: extract title from HTML or first line
        local title = string.match(body or "", "<title>(.-)</title>")
        if title and title ~= "" then return title end
        local line = string.match(body or "", "^%s*([^\r\n]+)")
        if line and line ~= "" and not string.match(line, "^<") then
            return string.sub(line, 1, 200)
        end
        return nil
    end
    local e = resp.error
    if type(e) == "table" and type(e.message) == "string" then
        -- trae quota / rate limit annotations
        if e.code then
            return tostring(e.code) .. ": " .. e.message
        end
        return e.message
    end
    if type(e) == "string" then return e end
    if type(resp.message) == "string" and resp.message ~= "" then
        if resp.code ~= nil then
            return tostring(resp.code) .. ": " .. resp.message
        end
        return resp.message
    end
    return nil
end

return adapter