package sipcall

import (
	"context"
	"crypto/rand"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"git.ipao.vip/rogee/go-sip/internal/asterisk"
	"os"
	"path/filepath"
	"time"
)

type Report struct {
	ID           string     `json:"id"`
	Directory    string     `json:"directory"`
	Line         string     `json:"line"`
	Server       string     `json:"server"`
	CallerID     string     `json:"caller_id"`
	Callee       string     `json:"callee"`
	DialedCallee string     `json:"dialed_callee"`
	CallID       string     `json:"sip_call_id,omitempty"`
	Status       string     `json:"status"`
	StartedAt    time.Time  `json:"started_at"`
	DialBoundAt  *time.Time `json:"pre_dial_bound_at,omitempty"`
	AnsweredAt   *time.Time `json:"answered_at,omitempty"`
	EndedAt      *time.Time `json:"end_confirmed_at,omitempty"`
	FinishedAt   time.Time  `json:"finished_at"`
	EndConfirmed bool       `json:"end_confirmed"`
	Debug        bool       `json:"debug"`
	Failure      string     `json:"failure,omitempty"`
	Evidence     *Evidence  `json:"evidence,omitempty"`
}

type testCall interface {
	Close() error
	EndConfirmed() bool
	Done() context.Context
}
type host interface {
	CheckIdle(context.Context) error
	Apply(context.Context, Config) (func() error, error)
	Dial(context.Context, asterisk.NativeDial) (testCall, error)
	Close() error
}
type captureSession interface {
	Stop(context.Context, string) (Evidence, error)
	Check() error
}
type captureStarter func(context.Context, Config, string) (captureSession, error)

// Run invokes exactly one call. Authorization is the operator's explicit
// command; this standalone tool never discovers, queues or retries tasks.
func Run(ctx context.Context, c Config, number string, debug bool) (*Report, error) {
	if _, err := c.Route(number); err != nil {
		return nil, err
	}
	h := &nativeHost{config: c}
	return run(ctx, c, number, debug, h, startCapture)
}

func run(ctx context.Context, c Config, number string, debug bool, h host, start captureStarter) (r *Report, err error) {
	route, err := c.Route(number)
	if err != nil {
		return nil, err
	}
	if _, err := privateConfigInfo(filepath.Join(c.ConfigDir, "pjsip.conf"), os.Geteuid()); err != nil {
		return nil, fmt.Errorf("configuration preflight: %w", err)
	}
	random := make([]byte, 12)
	if _, err = rand.Read(random); err != nil {
		return nil, err
	}
	id := "siptest-" + hex.EncodeToString(random)
	if err = ensureOutput(c.OutputDir); err != nil {
		return nil, err
	}
	dir := filepath.Join(c.OutputDir, id)
	if err = os.Mkdir(dir, 0700); err != nil {
		return nil, err
	}
	r = &Report{ID: id, Directory: dir, Line: c.ID, Server: fmt.Sprintf("%s:%d", c.Server, c.Port), CallerID: c.CallerID, Callee: number, DialedCallee: route, Status: "not_dialed", StartedAt: time.Now().UTC(), Debug: debug}
	var restore func() error
	var capture captureSession
	safeToRestore := true
	defer func() {
		cleanupCtx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
		defer cancel()
		if capture != nil {
			e, capErr := capture.Stop(cleanupCtx, r.CallID)
			r.Evidence = &e
			err = errors.Join(err, capErr)
			if r.AnsweredAt != nil && (e.FinalINVITECode < 200 || e.FinalINVITECode >= 300) {
				err = errors.Join(err, errors.New("debug evidence has no matching original INVITE 2xx final response for the observed native answer"))
			}
		}
		if restore != nil && safeToRestore {
			err = errors.Join(err, restore())
		}
		err = errors.Join(err, h.Close())
		r.FinishedAt = time.Now().UTC()
		if err != nil {
			r.Failure = err.Error()
			if r.Status == "connected" {
				r.Status = "failed"
			}
		}
		data, jsonErr := json.MarshalIndent(r, "", "  ")
		if jsonErr == nil {
			jsonErr = os.WriteFile(filepath.Join(dir, "result.json"), append(data, '\n'), 0600)
		}
		err = errors.Join(err, jsonErr)
	}()
	if err = ctx.Err(); err != nil {
		return r, err
	}
	if err = h.CheckIdle(ctx); err != nil {
		return r, fmt.Errorf("preflight: %w", err)
	}
	if debug {
		if c.Interface == "" {
			return r, errors.New("DEBUG_INTERFACE is required with --debug/-D")
		}
		capture, err = start(ctx, c, dir)
		if err != nil {
			return r, fmt.Errorf("capture preflight: %w", err)
		}
	}
	c.resultDir = dir
	restore, err = h.Apply(ctx, c)
	if err != nil {
		return r, fmt.Errorf("apply test line: %w", err)
	}
	if err = ctx.Err(); err != nil {
		return r, err
	}
	if err = h.CheckIdle(ctx); err != nil {
		return r, fmt.Errorf("pre-dial idle check: %w", err)
	}
	req := asterisk.NativeDial{ExecutionID: id, TrunkID: c.Endpoint(), DialedCallee: route, CallerID: c.CallerID, AnswerTimeout: c.Ring, BindSIPCall: func(_ string, callID string) error {
		if callID == "" {
			return errors.New("missing native SIP Call-ID")
		}
		if capture != nil {
			if e := capture.Check(); e != nil {
				return e
			}
		}
		r.CallID = callID
		now := time.Now().UTC()
		r.DialBoundAt = &now
		return nil
	}}
	r.Status = "not_connected"
	call, callErr := h.Dial(ctx, req)
	if callErr != nil {
		var failure *asterisk.NativeCallFailure
		if errors.As(callErr, &failure) && failure.ConfirmedEnd {
			r.EndConfirmed = true
			observed := time.Now().UTC()
			r.EndedAt = &observed
		} else if asterisk.NativeCallNeverSubmitted(callErr) {
			r.Status = "not_dialed"
		} else {
			safeToRestore = false
			r.Status = "unknown"
		}
		return r, callErr
	}
	now := time.Now().UTC()
	r.AnsweredAt = &now
	timer := time.NewTimer(c.Hold)
	defer timer.Stop()
	select {
	case <-timer.C:
	case <-call.Done().Done():
	case <-ctx.Done():
		err = ctx.Err()
	}
	err = errors.Join(err, call.Close())
	r.EndConfirmed = call.EndConfirmed()
	if !r.EndConfirmed {
		safeToRestore = false
		r.Status = "unknown"
		return r, errors.Join(err, errors.New("call termination unconfirmed; test configuration retained for manual diagnosis; do not retry"))
	}
	observed := time.Now().UTC()
	r.EndedAt = &observed
	r.Status = "connected"
	return r, err
}

func ensureOutput(path string) error {
	if err := os.MkdirAll(path, 0700); err != nil {
		return err
	}
	info, err := os.Lstat(path)
	if err != nil {
		return err
	}
	if !info.IsDir() || info.Mode()&os.ModeSymlink != 0 || info.Mode().Perm() != 0700 {
		return errors.New("OUTPUT_DIR must be a private real directory (0700)")
	}
	return nil
}