-- package.lua
-- Lumacs Package Manager
-- ============================================================================
-- Provides package installation, loading, and management similar to MELPA/lazy.nvim
--
-- Usage in packages.lua:
--   return {
--     "which-key",                              -- Short name (from registry)
--     { "evil-mode", lazy = true },             -- Lazy loaded
--     { url = "https://github.com/user/pkg" }, -- Git URL
--     { dir = "~/my-package" },                 -- Local directory
--   }
-- ============================================================================

local M = {}

-- Package manager state
M.packages = {}           -- Loaded packages: name -> module
M.package_specs = {}      -- Package specifications from packages.lua
M.loaded = {}             -- Track which packages are loaded
M.errors = {}             -- Track loading errors

-- Configuration
M.config = {
    -- Where user packages are installed
    install_path = os.getenv("HOME") .. "/.lumacs/packages",
    -- Where built-in packages live (in lumacs repo)
    builtin_path = "lua/packages",
    -- Bundled registry (shipped with lumacs)
    bundled_registry = "lua/core/registry.json",
    -- Registry URL (for short name resolution)
    registry_url = "https://raw.githubusercontent.com/lumacs/registry/main/registry.json",
    -- Local registry cache
    registry_cache = os.getenv("HOME") .. "/.lumacs/registry.json",
    -- Auto-install missing packages
    auto_install = true,
    -- Check for updates on startup
    check_updates = false,
}

-- Registry cache (populated from registry.json)
M.registry = {}

-- ============================================================================
-- Utility Functions
-- ============================================================================

-- Check if a file exists
local function file_exists(path)
    local f = io.open(path, "r")
    if f then
        f:close()
        return true
    end
    return false
end

-- Check if a directory exists
local function dir_exists(path)
    -- Use Lua's ability to open directory as file (returns nil for dirs on most systems)
    -- This is a simple heuristic; we'll improve with C++ integration later
    local f = io.open(path .. "/.", "r")
    if f then
        f:close()
        return true
    end
    -- Try another approach - check for init.lua or package.lua
    return file_exists(path .. "/init.lua") or file_exists(path .. "/package.lua")
end

-- Expand ~ to home directory
local function expand_path(path)
    if path:sub(1, 1) == "~" then
        return os.getenv("HOME") .. path:sub(2)
    end
    return path
end

-- Read entire file
local function read_file(path)
    local f = io.open(path, "r")
    if not f then return nil end
    local content = f:read("*a")
    f:close()
    return content
end

-- Write file
local function write_file(path, content)
    local f = io.open(path, "w")
    if not f then return false end
    f:write(content)
    f:close()
    return true
end

-- Simple JSON parser for registry (basic implementation)
local function parse_json_simple(str)
    -- Very basic JSON object parser for our simple registry format
    -- Format: { "name": { "url": "...", "path": "...", "description": "..." }, ... }
    local result = {}

    -- Remove outer braces and whitespace
    str = str:match("^%s*{(.*)}")
    if not str then return result end

    -- Match each package entry
    for name, content in str:gmatch('"([^"]+)"%s*:%s*({[^}]*})') do
        local entry = {}
        entry.url = content:match('"url"%s*:%s*"([^"]*)"')
        entry.path = content:match('"path"%s*:%s*"([^"]*)"')  -- Subpath in monorepo
        entry.description = content:match('"description"%s*:%s*"([^"]*)"')
        entry.version = content:match('"version"%s*:%s*"([^"]*)"')
        result[name] = entry
    end

    return result
end

-- ============================================================================
-- Package Specification Handling
-- ============================================================================

-- Normalize a package spec to standard format
local function normalize_spec(spec)
    if type(spec) == "string" then
        -- Simple string: package name
        return {
            name = spec,
            source = "name",
        }
    elseif type(spec) == "table" then
        local normalized = {}

        -- Handle array-style: { "name", options... }
        if spec[1] then
            normalized.name = spec[1]
            normalized.source = "name"
        end

        -- Handle explicit fields
        if spec.url then
            normalized.url = spec.url
            normalized.source = "git"
            normalized.name = normalized.name or spec.url:match("([^/]+)%.git$") or spec.url:match("([^/]+)$")
        end

        if spec.dir then
            normalized.dir = expand_path(spec.dir)
            normalized.source = "local"
            normalized.name = normalized.name or spec.dir:match("([^/]+)$")
        end

        -- Copy other options
        normalized.lazy = spec.lazy
        normalized.config = spec.config
        normalized.dependencies = spec.dependencies
        normalized.branch = spec.branch
        normalized.tag = spec.tag
        normalized.commit = spec.commit
        normalized.enabled = spec.enabled ~= false  -- Default to enabled

        return normalized
    end

    return nil
end

-- ============================================================================
-- Package Loading
-- ============================================================================

-- Find package path (checks builtin, then installed)
local function find_package_path(name)
    -- Check builtin packages first
    local builtin = M.config.builtin_path .. "/" .. name .. ".lua"
    if file_exists(builtin) then
        return builtin, "builtin"
    end

    -- Check builtin as directory
    local builtin_dir = M.config.builtin_path .. "/" .. name
    if file_exists(builtin_dir .. "/init.lua") then
        return builtin_dir .. "/init.lua", "builtin"
    end

    -- Check installed packages
    local installed = M.config.install_path .. "/" .. name
    if file_exists(installed .. "/init.lua") then
        return installed .. "/init.lua", "installed"
    end

    -- Check for single-file installed package
    local installed_file = M.config.install_path .. "/" .. name .. ".lua"
    if file_exists(installed_file) then
        return installed_file, "installed"
    end

    return nil, nil
end

-- Load a single package
function M.load_package(spec)
    local normalized = normalize_spec(spec)
    if not normalized then
        return false, "Invalid package specification"
    end

    if not normalized.enabled then
        return true, "Package disabled"
    end

    local name = normalized.name

    -- Already loaded?
    if M.loaded[name] then
        return true, "Already loaded"
    end

    -- Find the package
    local path, source

    if normalized.source == "local" then
        -- Local directory
        if file_exists(normalized.dir .. "/init.lua") then
            path = normalized.dir .. "/init.lua"
            source = "local"
        elseif file_exists(normalized.dir .. ".lua") then
            path = normalized.dir .. ".lua"
            source = "local"
        end
    else
        path, source = find_package_path(name)
    end

    if not path then
        -- Package not found - might need installation
        return false, "Package not found: " .. name
    end

    -- Load the package
    local ok, result = pcall(dofile, path)
    if not ok then
        M.errors[name] = result
        return false, "Error loading " .. name .. ": " .. tostring(result)
    end

    -- Store the package module
    M.packages[name] = result
    M.loaded[name] = {
        path = path,
        source = source,
        spec = normalized,
    }

    -- Run config function if provided
    if normalized.config and type(normalized.config) == "function" then
        local config_ok, config_err = pcall(normalized.config)
        if not config_ok then
            print("[package] Warning: config error for " .. name .. ": " .. tostring(config_err))
        end
    end

    return true, "Loaded from " .. source
end

-- Load all packages from specs
function M.load_all()
    local loaded_count = 0
    local error_count = 0

    for _, spec in ipairs(M.package_specs) do
        local normalized = normalize_spec(spec)
        if normalized and normalized.enabled and not normalized.lazy then
            local ok, msg = M.load_package(spec)
            if ok then
                loaded_count = loaded_count + 1
            else
                error_count = error_count + 1
                print("[package] " .. msg)
            end
        end
    end

    return loaded_count, error_count
end

-- ============================================================================
-- Package Installation (Git-based)
-- ============================================================================

-- Monorepo cache directory
M.monorepo_cache = os.getenv("HOME") .. "/.lumacs/repos"

-- Install a package from git
function M.install(spec)
    local normalized = normalize_spec(spec)
    if not normalized then
        return false, "Invalid package specification"
    end

    local name = normalized.name
    local url = normalized.url
    local subpath = nil  -- For monorepo packages

    -- Resolve URL and path from registry if needed
    if not url and M.registry[name] then
        url = M.registry[name].url
        subpath = M.registry[name].path
    end

    if not url then
        return false, "No URL found for package: " .. name
    end

    -- Create install directory
    local install_dir = M.config.install_path .. "/" .. name

    -- Check if already installed
    if dir_exists(install_dir) then
        return true, "Already installed"
    end

    -- Ensure parent directory exists
    os.execute("mkdir -p " .. M.config.install_path)

    if subpath then
        -- Monorepo installation: clone to cache, then copy subpath
        local repo_name = url:match("([^/]+)$") or "repo"
        local cache_dir = M.monorepo_cache .. "/" .. repo_name

        -- Clone or update the monorepo cache
        if not dir_exists(cache_dir) then
            os.execute("mkdir -p " .. M.monorepo_cache)
            local branch_opt = ""
            if normalized.branch then
                branch_opt = " -b " .. normalized.branch
            end
            local clone_cmd = string.format("git clone --depth 1%s %s %s 2>&1", branch_opt, url, cache_dir)
            local handle = io.popen(clone_cmd)
            local result = handle:read("*a")
            local success = handle:close()
            if not success then
                return false, "Failed to clone monorepo: " .. result
            end
        end

        -- Copy the specific package directory
        local src_dir = cache_dir .. "/" .. subpath
        if not dir_exists(src_dir) then
            return false, "Package path not found in monorepo: " .. subpath
        end

        local copy_cmd = string.format("cp -r %s %s 2>&1", src_dir, install_dir)
        local handle = io.popen(copy_cmd)
        local result = handle:read("*a")
        local success = handle:close()

        if success then
            return true, "Installed " .. name .. " (from monorepo)"
        else
            return false, "Failed to copy package: " .. result
        end
    else
        -- Standard single-repo installation
        local branch_opt = ""
        if normalized.branch then
            branch_opt = " -b " .. normalized.branch
        end

        local cmd = string.format("git clone --depth 1%s %s %s 2>&1", branch_opt, url, install_dir)
        local handle = io.popen(cmd)
        local result = handle:read("*a")
        local success = handle:close()

        if success then
            return true, "Installed " .. name
        else
            return false, "Failed to install " .. name .. ": " .. result
        end
    end
end

-- Update a package
function M.update(name)
    local install_dir = M.config.install_path .. "/" .. name

    if not dir_exists(install_dir) then
        return false, "Package not installed: " .. name
    end

    -- Check if this is a monorepo package
    if M.registry[name] and M.registry[name].path then
        local subpath = M.registry[name].path
        local url = M.registry[name].url
        local repo_name = url:match("([^/]+)$") or "repo"
        local cache_dir = M.monorepo_cache .. "/" .. repo_name

        -- Update the monorepo cache
        if dir_exists(cache_dir) then
            local pull_cmd = string.format("cd %s && git pull 2>&1", cache_dir)
            local handle = io.popen(pull_cmd)
            handle:read("*a")
            handle:close()
        end

        -- Re-copy the package
        local src_dir = cache_dir .. "/" .. subpath
        if dir_exists(src_dir) then
            os.execute(string.format("rm -rf %s", install_dir))
            local copy_cmd = string.format("cp -r %s %s 2>&1", src_dir, install_dir)
            local handle = io.popen(copy_cmd)
            local result = handle:read("*a")
            local success = handle:close()
            if success then
                return true, "Updated " .. name .. " (from monorepo)"
            else
                return false, "Failed to update " .. name .. ": " .. result
            end
        end
    end

    -- Standard git pull for single-repo packages
    local cmd = string.format("cd %s && git pull 2>&1", install_dir)
    local handle = io.popen(cmd)
    local result = handle:read("*a")
    local success = handle:close()

    if success then
        return true, result
    else
        return false, "Failed to update " .. name .. ": " .. result
    end
end

-- Remove a package
function M.remove(name)
    local install_dir = M.config.install_path .. "/" .. name

    if not dir_exists(install_dir) then
        return false, "Package not installed: " .. name
    end

    local cmd = string.format("rm -rf %s 2>&1", install_dir)
    local success = os.execute(cmd)

    if success then
        M.packages[name] = nil
        M.loaded[name] = nil
        return true, "Removed " .. name
    else
        return false, "Failed to remove " .. name
    end
end

-- ============================================================================
-- Registry Management
-- ============================================================================

-- Load registry from cache or bundled
function M.load_registry()
    -- Try user cache first
    local content = read_file(M.config.registry_cache)
    if content then
        M.registry = parse_json_simple(content)
        return true
    end

    -- Fall back to bundled registry
    content = read_file(M.config.bundled_registry)
    if content then
        M.registry = parse_json_simple(content)
        return true
    end

    return false
end

-- Update registry from remote
function M.update_registry()
    -- This would use curl/wget - for now we'll use a Lua HTTP library or shell
    local cmd = string.format("curl -s %s -o %s 2>&1", M.config.registry_url, M.config.registry_cache)
    local success = os.execute(cmd)

    if success then
        return M.load_registry()
    end
    return false
end

-- ============================================================================
-- Setup and Initialization
-- ============================================================================

-- Setup the package manager
function M.setup(opts)
    opts = opts or {}

    -- Merge config
    for k, v in pairs(opts) do
        M.config[k] = v
    end

    -- Ensure directories exist
    os.execute("mkdir -p " .. M.config.install_path)

    -- Load registry
    M.load_registry()

    -- Load package specs if packages.lua exists
    local packages_file = os.getenv("HOME") .. "/.lumacs/packages.lua"
    if file_exists(packages_file) then
        local ok, specs = pcall(dofile, packages_file)
        if ok and type(specs) == "table" then
            M.package_specs = specs
        end
    end

    -- Auto-install missing packages
    if M.config.auto_install then
        for _, spec in ipairs(M.package_specs) do
            local normalized = normalize_spec(spec)
            if normalized and normalized.enabled and normalized.source == "name" then
                local path = find_package_path(normalized.name)
                if not path and M.registry[normalized.name] then
                    print("[package] Auto-installing " .. normalized.name .. "...")
                    M.install(spec)
                end
            end
        end
    end

    return M
end

-- Get package info
function M.info(name)
    local info = {
        name = name,
        loaded = M.loaded[name] ~= nil,
        installed = false,
        builtin = false,
        registry = M.registry[name],
    }

    local path, source = find_package_path(name)
    if path then
        info.installed = true
        info.path = path
        info.source = source
        info.builtin = (source == "builtin")
    end

    if M.loaded[name] then
        info.load_info = M.loaded[name]
    end

    return info
end

-- List all available packages
function M.list_available()
    local packages = {}

    -- Builtin packages
    local builtin_dir = M.config.builtin_path
    -- Note: We'd need to enumerate directory - for now, rely on what's loaded

    -- Registry packages
    for name, entry in pairs(M.registry) do
        packages[name] = {
            name = name,
            source = "registry",
            description = entry.description,
            url = entry.url,
        }
    end

    -- Loaded packages
    for name, info in pairs(M.loaded) do
        packages[name] = packages[name] or {}
        packages[name].name = name
        packages[name].loaded = true
        packages[name].source = info.source
        packages[name].path = info.path
    end

    return packages
end

-- List loaded packages
function M.list_loaded()
    local result = {}
    for name, info in pairs(M.loaded) do
        table.insert(result, {
            name = name,
            source = info.source,
            path = info.path,
        })
    end
    table.sort(result, function(a, b) return a.name < b.name end)
    return result
end

-- ============================================================================
-- Module Export
-- ============================================================================

return M