// Package claudecode is the claude-code harness adapter.
package claudecode

import (
	"os"
	"path/filepath"

	"github.com/lukaszraczylo/harness-sync/internal/adapter"
	"github.com/lukaszraczylo/harness-sync/internal/adapter/common"
	"github.com/lukaszraczylo/harness-sync/internal/canonical"
)

const name = "claude-code"

// Adapter implements adapter.Adapter for the claude-code harness.
type Adapter struct {
	home string
}

// Option configures an Adapter.
type Option func(*Adapter)

// WithHome overrides the home directory (defaults to os.UserHomeDir).
func WithHome(h string) Option { return func(a *Adapter) { a.home = h } }

// New returns a new Adapter with the given options applied.
func New(opts ...Option) *Adapter {
	a := &Adapter{home: defaultHome()}
	for _, o := range opts {
		o(a)
	}
	return a
}

func defaultHome() string {
	h, err := os.UserHomeDir()
	if err != nil {
		return ""
	}
	return h
}

// Name returns the harness identifier.
func (a *Adapter) Name() string { return name }

// Detect returns true when ~/.claude exists.
func (a *Adapter) Detect() bool {
	_, err := os.Stat(filepath.Join(a.home, ".claude"))
	return err == nil
}

// Render produces the FileSet that applies the canonical bundle to claude-code.
// settings.json is MERGED into any existing file so user-managed keys
// settings.json is MERGED into any existing file so user-managed keys
// (hooks, permissions, env, …) are preserved.
func (a *Adapter) Render(b *canonical.Bundle) (*adapter.FileSet, error) {
	fs := adapter.NewFileSet()
	base := filepath.Join(a.home, ".claude")

	fs.Add(adapter.File{
		Dest:          filepath.Join(base, "skills"),
		Kind:          adapter.SymlinkDir,
		SymlinkTarget: filepath.Join(b.Root, "skills"),
	})
	fs.Add(adapter.File{
		Dest:          filepath.Join(base, "agents"),
		Kind:          adapter.SymlinkDir,
		SymlinkTarget: filepath.Join(b.Root, "agents"),
	})

	instructions := b.Instructions.Global
	if override, ok := b.Instructions.PerHarness[name]; ok && override != "" {
		instructions = override
	}
	fs.Add(adapter.File{
		Dest:    filepath.Join(base, "CLAUDE.md"),
		Kind:    adapter.RenderedFile,
		Content: []byte(instructions),
	})

	// settings.json holds the gateway env vars + model override.
	// Only emit when a gateway URL is configured.
	if b.Profile.Gateway.URL != "" {
		settingsPath := filepath.Join(base, "settings.json")
		settingsExisting, _ := os.ReadFile(settingsPath)
		settingsOverlay := map[string]any{
			"model": b.Profile.Gateway.DefaultModel,
			"env": map[string]any{
				"ANTHROPIC_BASE_URL":   b.Profile.Gateway.URL,
				"ANTHROPIC_AUTH_TOKEN": b.Profile.Gateway.Token,
			},
		}
		settingsMerged, err := common.MergeJSONKeys(settingsExisting, settingsOverlay)
		if err != nil {
			return nil, err
		}
		fs.Add(adapter.File{
			Dest:    settingsPath,
			Kind:    adapter.RenderedFile,
			Content: settingsMerged,
		})
	}

	// Claude Code reads MCP servers from two files on disk:
	//   * ~/.claude.json (live, written by `claude mcp add`)
	//   * ~/.claude/mcp_servers.json (older / fallback location)
	// Write the dedicated file as the canonical destination, AND merge the
	// same map into ~/.claude.json (preserving every other key in that
	// large state file) so both stay in sync.
	mcpMap := common.BuildMCPMapStyled(&b.MCP, common.MCPClaudeStyle)
	overlay := map[string]any{"mcpServers": mcpMap}

	dedicatedPath := filepath.Join(base, "mcp_servers.json")
	dedicatedExisting, _ := os.ReadFile(dedicatedPath)
	dedicatedMerged, err := common.MergeJSONKeys(dedicatedExisting, overlay)
	if err != nil {
		return nil, err
	}
	fs.Add(adapter.File{
		Dest:    dedicatedPath,
		Kind:    adapter.RenderedFile,
		Content: dedicatedMerged,
	})

	livePath := filepath.Join(a.home, ".claude.json")
	if _, err := os.Stat(livePath); err == nil {
		liveExisting, _ := os.ReadFile(livePath)
		liveMerged, err := common.MergeJSONKeys(liveExisting, overlay)
		if err != nil {
			return nil, err
		}
		fs.Add(adapter.File{
			Dest:    livePath,
			Kind:    adapter.RenderedFile,
			Content: liveMerged,
		})
	}

	return fs, nil
}

// Import reads claude-code config from home and returns a canonical ImportResult.
func (a *Adapter) Import(home string) (*adapter.ImportResult, error) {
	return importFrom(home)
}