package claude

import (
	"context"
	"encoding/json"
	"fmt"
	"regexp"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/yaoapp/gou/connector"
	"github.com/yaoapp/gou/store"
	agentContext "github.com/yaoapp/yao/agent/context"
	"github.com/yaoapp/yao/agent/sandbox/v2/types"
	infra "github.com/yaoapp/yao/sandbox/v2"
)

const defaultA2OPort = 3099

var yaoSessionNS = uuid.MustParse("f47ac10b-58cc-4372-a567-0e02b2c3d479")

var safeNameRe = regexp.MustCompile(`[^a-zA-Z0-9_\-.]`)

func chatIDToSessionUUID(assistantID, chatID string) string {
	return uuid.NewSHA1(yaoSessionNS, []byte(assistantID+":"+chatID)).String()
}

func sanitizeSessionName(chatID string) string {
	return "yao-" + safeNameRe.ReplaceAllString(chatID, "_")
}

func chatSessionExists(storeKey string) bool {
	s, err := store.Get("__yao.store")
	if err != nil {
		return false
	}
	return s.Has(storeKey)
}

func markChatSession(storeKey, sessionUUID string, ttl time.Duration) {
	s, err := store.Get("__yao.store")
	if err != nil {
		return
	}
	s.Set(storeKey, sessionUUID, ttl)
}

type command struct {
	shell   []string
	env     map[string]string
	stdin   []byte
	workDir string
}

func (r *Runner) buildCommand(ctx context.Context, req *types.StreamRequest, p platform) command {
	computer := req.Computer
	workDir := computer.GetWorkDir()
	assistantID := req.AssistantID
	chatID := req.ChatID

	var isContinuation bool
	if chatID != "" {
		storeKey := "claude-session:" + assistantID + ":" + chatID
		isContinuation = chatSessionExists(storeKey)
	} else {
		isContinuation = hasExistingSession(ctx, computer, p, assistantID)
	}

	env := buildEnv(req, p)
	args := buildArgs(req, r, p, isContinuation, assistantID, chatID)
	inputJSONL := buildLastUserMessageJSONL(req.Messages)

	var systemPrompt string
	envPrompt := buildSandboxEnvPrompt(p, workDir)
	if !isContinuation && req.SystemPrompt != "" {
		systemPrompt = req.SystemPrompt + "\n\n" + envPrompt
	} else if !isContinuation {
		systemPrompt = envPrompt
	}

	promptFile := p.PathJoin(workDir, ".yao", "assistants", assistantID, "system-prompt.txt")
	if assistantID == "" {
		promptFile = p.PathJoin(workDir, ".yao", ".system-prompt.txt")
	}

	script, stdin := p.BuildScript(scriptInput{
		args:         args,
		systemPrompt: systemPrompt,
		inputJSONL:   inputJSONL,
		workDir:      workDir,
		promptFile:   promptFile,
	})

	return command{
		shell:   p.ShellCmd(script),
		env:     env,
		stdin:   stdin,
		workDir: workDir,
	}
}

func buildEnv(req *types.StreamRequest, p platform) map[string]string {
	env := make(map[string]string)
	workDir := req.Computer.GetWorkDir()

	for k, v := range p.HomeEnv(workDir) {
		env[k] = v
	}
	env["WORKDIR"] = workDir

	assistantID := req.AssistantID
	if assistantID != "" {
		configDir := p.PathJoin(workDir, ".yao", "assistants", assistantID)
		env["CLAUDE_CONFIG_DIR"] = configDir
		env["CTX_ASSISTANT_ID"] = assistantID
		// CTX_SKILLS_DIR: absolute path to the skills directory inside the sandbox.
		// Use this in skill scripts instead of constructing the path manually,
		// so it works correctly on all platforms (Linux, macOS, Windows).
		env["CTX_SKILLS_DIR"] = p.PathJoin(workDir, ".yao", "assistants", assistantID, "skills")
	}

	if req.Connector != nil {
		setting := req.Connector.Setting()
		host, _ := setting["host"].(string)
		key, _ := setting["key"].(string)
		model, _ := setting["model"].(string)

		if req.Connector.Is(connector.ANTHROPIC) {
			env["ANTHROPIC_BASE_URL"] = host
			env["ANTHROPIC_API_KEY"] = key
			if model != "" {
				env["ANTHROPIC_MODEL"] = model
				env["ANTHROPIC_DEFAULT_OPUS_MODEL"] = model
				env["ANTHROPIC_DEFAULT_SONNET_MODEL"] = model
				env["ANTHROPIC_DEFAULT_HAIKU_MODEL"] = model
				env["CLAUDE_CODE_SUBAGENT_MODEL"] = model
			}
		} else {
			connectorID := req.Connector.ID()
			env["ANTHROPIC_BASE_URL"] = fmt.Sprintf("http://127.0.0.1:%d/c/%s", defaultA2OPort, connectorID)
			env["ANTHROPIC_API_KEY"] = "dummy"
			// Use a valid Anthropic model name to pass Claude CLI's local
			// validation. The a2o proxy ignores this and substitutes the
			// real backend model from its connector config.
			env["ANTHROPIC_MODEL"] = "claude-sonnet-4-6"
			env["ANTHROPIC_DEFAULT_OPUS_MODEL"] = "claude-sonnet-4-6"
			env["ANTHROPIC_DEFAULT_SONNET_MODEL"] = "claude-sonnet-4-6"
			env["ANTHROPIC_DEFAULT_HAIKU_MODEL"] = "claude-sonnet-4-6"
			env["CLAUDE_CODE_SUBAGENT_MODEL"] = "claude-sonnet-4-6"
		}

		if thinking, ok := setting["thinking"].(map[string]interface{}); ok {
			thinkType, _ := thinking["type"].(string)
			switch thinkType {
			case "disabled":
				env["MAX_THINKING_TOKENS"] = "0"
			case "enabled":
				if budget, ok := thinking["budget_tokens"].(float64); ok && budget > 0 {
					env["MAX_THINKING_TOKENS"] = fmt.Sprintf("%d", int(budget))
				}
			}
		}
	}

	if req.Config != nil && len(req.Config.Secrets) > 0 {
		for k, v := range req.Config.Secrets {
			env[k] = v
		}
	}

	if req.Token != nil {
		if req.Token.Token != "" {
			env["YAO_TOKEN"] = req.Token.Token
		}
		if req.Token.RefreshToken != "" {
			env["YAO_REFRESH_TOKEN"] = req.Token.RefreshToken
		}
	}

	return env
}

func buildArgs(req *types.StreamRequest, r *Runner, p platform, isContinuation bool, assistantID, chatID string) []string {
	var args []string

	permMode := ""
	if req.Config != nil && req.Config.Runner.Options != nil {
		if v, ok := req.Config.Runner.Options["permission_mode"]; ok {
			permMode = fmt.Sprintf("%v", v)
		}
	}
	if permMode == "bypassPermissions" {
		args = append(args, "--dangerously-skip-permissions")
		args = append(args, "--permission-mode", permMode)
	}

	args = append(args, "--input-format", "stream-json")
	args = append(args, "--output-format", "stream-json")
	args = append(args, "--include-partial-messages")
	args = append(args, "--verbose")

	if chatID != "" {
		sessionUUID := chatIDToSessionUUID(assistantID, chatID)
		sessionName := sanitizeSessionName(chatID)
		if isContinuation {
			args = append(args, "--resume", sessionUUID)
		} else {
			args = append(args, "--session-id", sessionUUID)
		}
		args = append(args, "--name", sessionName)
	} else if isContinuation {
		args = append(args, "--continue")
	}

	if req.Config != nil && req.Config.Runner.Options != nil {
		for key, val := range req.Config.Runner.Options {
			if flag, ok := claudeArgWhitelist[key]; ok {
				args = append(args, flag, fmt.Sprintf("%v", val))
			}
		}
	}

	if r.hasMCP {
		workDir := req.Computer.GetWorkDir()
		mcpPath := p.PathJoin(workDir, ".yao", "assistants", assistantID, "mcp.json")
		if assistantID == "" {
			mcpPath = p.PathJoin(workDir, ".claude", "mcp.json")
		}
		args = append(args, "--mcp-config", mcpPath)
		if r.mcpToolPattern != "" {
			args = append(args, "--allowedTools", r.mcpToolPattern)
		}
	}

	return args
}

func buildSandboxEnvPrompt(p platform, workDir string) string {
	osName := p.OS()
	if osName == "" {
		osName = "linux"
	}
	shell := p.Shell()
	if shell == "" {
		shell = "bash"
	}

	shellNote := p.EnvPromptNote()

	envVarSyntax := "$VAR_NAME"
	if osName == "windows" {
		envVarSyntax = "$env:VAR_NAME"
	}

	return fmt.Sprintf(`## Sandbox Environment

- **Operating System**: %[2]s
- **Shell**: %[3]s
- **Working Directory**: %[1]s
- **File Access**: You have full read/write access to %[1]s
- **Environment variable syntax**: `+"`%[5]s`"+` (e.g. `+"`$CTX_SKILLS_DIR`"+` on POSIX, `+"`$env:CTX_SKILLS_DIR`"+` on Windows)%[4]s

## User Attachments

User-uploaded files (images, documents, code files, etc.) are placed in %[1]s/.attachments/{chatID}/
Each chat session has its own subdirectory to avoid conflicts.
When the user references an attached file, read it from this directory using the Read or Bash tool.
For image files, you can view them directly as Claude supports vision on local files.
`, workDir, osName, shell, shellNote, envVarSyntax)
}

func hasExistingSession(ctx context.Context, computer infra.Computer, p platform, assistantID string) bool {
	workDir := computer.GetWorkDir()
	var sessionDir string
	if assistantID != "" {
		configDir := p.PathJoin(workDir, ".yao", "assistants", assistantID)
		sessionDir = p.PathJoin(configDir, "projects")
	} else {
		sessionDir = p.PathJoin(workDir, ".claude", "projects")
	}
	result, err := computer.Exec(ctx, p.ListDirCmd(sessionDir))
	if err != nil || result.ExitCode != 0 {
		return false
	}
	return strings.TrimSpace(result.Stdout) != ""
}

func buildMCPConfig(servers []types.MCPServer) []byte {
	mcpServers := make(map[string]any, len(servers))
	for _, s := range servers {
		name := s.ServerID
		if name == "" {
			continue
		}
		mcpServers[name] = map[string]any{
			"command": "tai",
			"args":    []string{"mcp", name},
		}
	}
	if len(mcpServers) == 0 {
		mcpServers["yao"] = map[string]any{
			"command": "tai",
			"args":    []string{"mcp"},
		}
	}
	config := map[string]any{"mcpServers": mcpServers}
	data, _ := json.Marshal(config)
	return data
}

func buildMCPAllowedTools(servers []types.MCPServer) string {
	patterns := make([]string, 0, len(servers))
	for _, s := range servers {
		if s.ServerID != "" {
			patterns = append(patterns, fmt.Sprintf("mcp__%s__*", s.ServerID))
		}
	}
	if len(patterns) == 0 {
		return "mcp__yao__*"
	}
	return strings.Join(patterns, ",")
}

func buildLastUserMessageJSONL(messages []agentContext.Message) string {
	for i := len(messages) - 1; i >= 0; i-- {
		if messages[i].Role == "user" {
			content := messages[i].Content
			if content == nil {
				content = ""
			}
			msg := map[string]any{
				"type": "user",
				"message": map[string]any{
					"role":    "user",
					"content": content,
				},
			}
			data, _ := json.Marshal(msg)
			return string(data)
		}
	}
	return ""
}

var claudeArgWhitelist = map[string]string{
	"max_turns":        "--max-turns",
	"disallowed_tools": "--disallowed-tools",
	"allowed_tools":    "--allowedTools",
}