// Package renode installs the Renode emulator (AUR), arm-none-eabi-gdb,
// the arduino-sim helper script, and wokwi-cli.
package renode

import (
	"bytes"
	"context"
	"embed"
	"fmt"
	"os"
	"path/filepath"
	"text/template"

	"gitlab.hive-brain.de/MDietermann/Archduino/internal/config"
	"gitlab.hive-brain.de/MDietermann/Archduino/internal/module"
	"gitlab.hive-brain.de/MDietermann/Archduino/internal/platform"
)

//go:embed assets/arduino-sim.tmpl
var assetsFS embed.FS

// Module installs Renode and adjacent emulator tooling.
type Module struct {
	cfg config.RenodeConfig
	pm  platform.PackageManager
	aur platform.AURHelper
}

// New constructs a renode Module.
func New(cfg config.RenodeConfig, pm platform.PackageManager, aur platform.AURHelper) Module {
	return Module{cfg: cfg, pm: pm, aur: aur}
}

type state struct {
	RenodeInstalled  bool
	GdbInstalled     bool
	SimScriptCurrent bool
	WokwiInstalled   bool
	RenderedSim      []byte
	SimPath          string
	WokwiPath        string
}

// Meta returns the module metadata.
func (Module) Meta() module.Meta {
	return module.Meta{ID: "renode", Name: "Renode emulator", Description: "Install Renode, ARM GDB, arduino-sim helper, and Wokwi CLI."}
}

func binPath() (string, error) {
	h, err := os.UserHomeDir()
	if err != nil {
		return "", err
	}
	return filepath.Join(h, ".local", "bin"), nil
}

func (m Module) renderSim() ([]byte, error) {
	tmplBytes, err := assetsFS.ReadFile("assets/arduino-sim.tmpl")
	if err != nil {
		return nil, err
	}
	tmpl, err := template.New("sim").Parse(string(tmplBytes))
	if err != nil {
		return nil, err
	}
	var buf bytes.Buffer
	if err := tmpl.Execute(&buf, m.cfg); err != nil {
		return nil, err
	}
	return buf.Bytes(), nil
}

// Detect inspects the system and returns current state.
func (m Module) Detect(ctx context.Context) (module.State, error) {
	bin, err := binPath()
	if err != nil {
		return nil, err
	}
	s := state{
		SimPath:   filepath.Join(bin, "arduino-sim"),
		WokwiPath: filepath.Join(bin, "wokwi-cli"),
	}
	if ok, err := m.pm.IsInstalled(ctx, "renode-bin"); err == nil && ok {
		s.RenodeInstalled = true
	}
	if ok, err := m.pm.IsInstalled(ctx, "arm-none-eabi-gdb"); err == nil && ok {
		s.GdbInstalled = true
	}

	rendered, err := m.renderSim()
	if err != nil {
		return nil, err
	}
	s.RenderedSim = rendered
	if cur, err := os.ReadFile(s.SimPath); err == nil && bytes.Equal(cur, rendered) {
		s.SimScriptCurrent = true
	}
	if _, err := os.Stat(s.WokwiPath); err == nil {
		s.WokwiInstalled = true
	}
	return s, nil
}

// Plan computes the set of actions needed to converge to desired state.
func (m Module) Plan(ctx context.Context, cur module.State) (module.Plan, error) {
	s, _ := cur.(state)
	var actions []module.Action

	if !s.RenodeInstalled {
		actions = append(actions, module.Action{
			Description: "ensure yay installed",
			Kind:        module.ActionPackageInstall,
			Exec:        func(ctx context.Context) error { return m.aur.EnsureInstalled(ctx) },
		})
		actions = append(actions, module.Action{
			Description: "yay install renode-bin",
			Kind:        module.ActionPackageInstall,
			Exec:        func(ctx context.Context) error { return m.aur.Install(ctx, []string{"renode-bin"}) },
		})
	}
	if !s.GdbInstalled {
		actions = append(actions, module.Action{
			Description: "pacman install arm-none-eabi-gdb",
			Kind:        module.ActionPackageInstall,
			Exec:        func(ctx context.Context) error { return m.pm.Install(ctx, []string{"arm-none-eabi-gdb"}) },
		})
	}
	if !s.SimScriptCurrent {
		rendered := append([]byte{}, s.RenderedSim...)
		path := s.SimPath
		actions = append(actions, module.Action{
			Description: "write arduino-sim helper",
			Kind:        module.ActionFileWrite,
			Exec: func(ctx context.Context) error {
				return platform.WriteUserFile(path, rendered, 0o755)
			},
		})
	}
	if !s.WokwiInstalled {
		url := m.cfg.WokwiURL
		dst := s.WokwiPath
		actions = append(actions, module.Action{
			Description: "download wokwi-cli " + m.cfg.WokwiVersion,
			Kind:        module.ActionFileWrite,
			Exec: func(ctx context.Context) error {
				if err := os.MkdirAll(filepath.Dir(dst), 0o755); err != nil {
					return err
				}
				return platform.Download(ctx, url, dst, 0o755)
			},
		})
	}
	return module.Plan{Actions: actions}, nil
}

// Apply executes the planned actions in order.
func (m Module) Apply(ctx context.Context, p module.Plan, r module.Reporter) error {
	for i, a := range p.Actions {
		r.Progress(m.Meta().ID, i+1, len(p.Actions), a.Description)
		if err := a.Exec(ctx); err != nil {
			return err
		}
	}
	return nil
}

// Verify re-Detects and errors if state hasn't converged.
func (m Module) Verify(ctx context.Context) error {
	st, err := m.Detect(ctx)
	if err != nil {
		return err
	}
	s := st.(state)
	if !s.RenodeInstalled {
		return fmt.Errorf("renode-bin not installed")
	}
	if !s.GdbInstalled {
		return fmt.Errorf("arm-none-eabi-gdb not installed")
	}
	if !s.SimScriptCurrent {
		return fmt.Errorf("arduino-sim script drift")
	}
	if !s.WokwiInstalled {
		return fmt.Errorf("wokwi-cli missing")
	}
	return nil
}

func (m Module) PlanForce(ctx context.Context) (module.Plan, error) {
	bin, err := binPath()
	if err != nil {
		return module.Plan{}, err
	}
	rendered, err := m.renderSim()
	if err != nil {
		return module.Plan{}, err
	}
	simPath := filepath.Join(bin, "arduino-sim")
	wokwiPath := filepath.Join(bin, "wokwi-cli")

	actions := []module.Action{
		{
			Description: "ensure yay installed",
			Kind:        module.ActionPackageInstall,
			Exec:        func(ctx context.Context) error { return m.aur.EnsureInstalled(ctx) },
		},
		{
			Description: "yay -S (force) renode-bin",
			Kind:        module.ActionPackageInstall,
			Exec:        func(ctx context.Context) error { return m.aur.Reinstall(ctx, []string{"renode-bin"}) },
		},
		{
			Description: "pacman -S (force) arm-none-eabi-gdb",
			Kind:        module.ActionPackageInstall,
			Exec:        func(ctx context.Context) error { return m.pm.Reinstall(ctx, []string{"arm-none-eabi-gdb"}) },
		},
		{
			Description: "rewrite arduino-sim helper (force)",
			Kind:        module.ActionFileWrite,
			Exec: func(ctx context.Context) error {
				return platform.WriteUserFile(simPath, rendered, 0o755)
			},
		},
		{
			Description: "redownload wokwi-cli " + m.cfg.WokwiVersion + " (force)",
			Kind:        module.ActionFileWrite,
			Exec: func(ctx context.Context) error {
				if err := os.MkdirAll(filepath.Dir(wokwiPath), 0o755); err != nil {
					return err
				}
				return platform.Download(ctx, m.cfg.WokwiURL, wokwiPath, 0o755)
			},
		},
	}
	return module.Plan{Actions: actions}, nil
}