// Package tdclient is a minimal terdut-server API client for the operator's
// own controllers. It mirrors the shape of terdut-tui's
// internal/api/client.go (baseURL/httpClient fields, a shared do/statusError
// helper, per terdut/CLAUDE.md's "any change to a server endpoint or JSON
// shape must be mirrored" convention) but authorizes with a Bearer API key
// rather than a session cookie — the operator never signs in as a human
// (DESIGN.md §6).
package tdclient

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"strings"
	"time"
)

// Client talks to one terdut-server install, optionally as a service
// account. A zero-value token works for endpoints that don't need one
// (Version, Bootstrap).

// fieldName is the JSON key every create/rename request body below shares.
const fieldName = "name"

// fieldKind is the JSON key an integration's create request body shares
// with the terdutv1alpha1.TerdutAlertSourceSpec field of the same name.
const fieldKind = "kind"

type Client struct {
	baseURL    string
	httpClient *http.Client
	token      string
}

// New creates a Client against baseURL, with no credential set.
func New(baseURL string) *Client {
	return &Client{
		baseURL:    strings.TrimRight(baseURL, "/"),
		httpClient: &http.Client{Timeout: 10 * time.Second},
	}
}

// WithToken returns a copy of c that authorizes every request as a Bearer
// credential — a user's own API key or a service-account key
// (SERVICE-ACCOUNTS.md), the server resolves either the same way.
func (c *Client) WithToken(token string) *Client {
	cp := *c
	cp.token = token
	return &cp
}

// StatusError is a non-2xx response — the server's {"error": "..."} body
// decoded into Message, same shape terdut-tui's client uses.
type StatusError struct {
	Code    int
	Message string
}

// ignoreNotFound turns a 404 into success. Every DELETE here is idempotent: the
// thing already being gone is the outcome the caller wanted, and a finalizer
// that failed on it could never be removed.
func ignoreNotFound(err error) error {
	if se, ok := errors.AsType[*StatusError](err); ok && se.Code == http.StatusNotFound {
		return nil
	}
	return err
}

func (e *StatusError) Error() string {
	if e.Message != "" {
		return fmt.Sprintf("server returned %d: %s", e.Code, e.Message)
	}
	return fmt.Sprintf("server returned %d", e.Code)
}

func statusError(resp *http.Response) error {
	var e struct {
		Error string `json:"error"`
	}
	_ = json.NewDecoder(resp.Body).Decode(&e)
	return &StatusError{Code: resp.StatusCode, Message: e.Error}
}

func (c *Client) newRequest(ctx context.Context, method, path string, body any) (*http.Request, error) {
	var reader *strings.Reader
	if body != nil {
		data, err := json.Marshal(body)
		if err != nil {
			return nil, err
		}
		reader = strings.NewReader(string(data))
	}
	var req *http.Request
	var err error
	if reader != nil {
		req, err = http.NewRequestWithContext(ctx, method, c.baseURL+path, reader)
	} else {
		req, err = http.NewRequestWithContext(ctx, method, c.baseURL+path, nil)
	}
	if err != nil {
		return nil, err
	}
	req.Header.Set("Accept", "application/json")
	if body != nil {
		req.Header.Set("Content-Type", "application/json")
	}
	if c.token != "" {
		req.Header.Set("Authorization", "Bearer "+c.token)
	}
	return req, nil
}

func (c *Client) do(req *http.Request, out any) error {
	resp, err := c.httpClient.Do(req)
	if err != nil {
		return err
	}
	defer func() { _ = resp.Body.Close() }()
	if resp.StatusCode >= 400 {
		return statusError(resp)
	}
	if out != nil {
		return json.NewDecoder(resp.Body).Decode(out)
	}
	return nil
}

// Team mirrors terdut-server's models.Team (internal/models/team.go), minus
// Role/Source, which are only ever populated for a human caller's own
// membership and never apply to a service account's view of a team.
type Team struct {
	ID         int64   `json:"id"`
	Name       string  `json:"name"`
	ExternalID *string `json:"external_id,omitempty"`
}

// CreateTeam calls POST /api/teams with an external_id, which makes it
// idempotent: a team that already carries that id is returned (200) instead of
// created (201), so a client that crashed before recording the id finds its own
// team again. A StatusError with Code 409 means the name belongs to a different
// team. Needs an instance-scoped credential.
func (c *Client) CreateTeam(ctx context.Context, name, externalID string) (*Team, error) {
	req, err := c.newRequest(ctx, http.MethodPost, "/api/teams",
		map[string]string{fieldName: name, "external_id": externalID})
	if err != nil {
		return nil, err
	}
	var team Team
	if err := c.do(req, &team); err != nil {
		return nil, err
	}
	return &team, nil
}

// RenameTeam calls PUT /api/teams/{teamID} — owner-gated server-side
// (requireTeamOwner), so c must hold this team's own team-scoped
// credential, not the instance-scoped one CreateTeam used.
func (c *Client) RenameTeam(ctx context.Context, teamID int64, name string) error {
	req, err := c.newRequest(ctx, http.MethodPut,
		fmt.Sprintf("/api/teams/%d", teamID), map[string]string{fieldName: name})
	if err != nil {
		return err
	}
	return c.do(req, nil)
}

// DeleteTeam calls DELETE /api/teams/{teamID} — owner-gated, same
// credential requirement as RenameTeam. terdut-server refuses this while
// the team has open incidents (409) — surfaced to the caller as a
// StatusError, not retried specially here.
func (c *Client) DeleteTeam(ctx context.Context, teamID int64) error {
	req, err := c.newRequest(ctx, http.MethodDelete, fmt.Sprintf("/api/teams/%d", teamID), nil)
	if err != nil {
		return err
	}
	return ignoreNotFound(c.do(req, nil))
}

// SetTeamOIDCGroups calls PUT /api/teams/{teamID}/oidc-groups — owner-gated,
// same credential requirement as RenameTeam. An empty group string clears
// that binding server-side (terdut-server's own NULLIF handling).
func (c *Client) SetTeamOIDCGroups(ctx context.Context, teamID int64, memberGroup, ownerGroup string) error {
	req, err := c.newRequest(ctx, http.MethodPut,
		fmt.Sprintf("/api/teams/%d/oidc-groups", teamID),
		map[string]string{"member_group": memberGroup, "owner_group": ownerGroup})
	if err != nil {
		return err
	}
	return c.do(req, nil)
}

// EscalationTargetRequest/EscalationLevelRequest/SetEscalationRequest mirror
// terdut-server's escalationTargetJSON/escalationLevelJSON/escalationJSON
// (internal/api/escalation.go) -- the PUT body, not the richer GET response
// (escalationView), which this client never needs to decode since the
// controller always computes its own desired state fresh from spec.
type EscalationTargetRequest struct {
	Kind string `json:"kind"`
	// Username names the person for a "user" target; the server resolves it.
	Username string `json:"username,omitempty"`
}

type EscalationLevelRequest struct {
	Position       int64                     `json:"position"`
	TimeoutSeconds int64                     `json:"timeout_seconds"`
	Targets        []EscalationTargetRequest `json:"targets"`
}

type SetEscalationRequest struct {
	RepeatCount   int64                    `json:"repeat_count"`
	FallbackTopic string                   `json:"fallback_topic"`
	Levels        []EscalationLevelRequest `json:"levels"`
}

// SetEscalation calls PUT /api/teams/{teamID}/escalation -- an upsert
// server-side (confirmed against source: `INSERT ... ON CONFLICT (team_id)
// DO UPDATE`), so there is no separate create step for this resource at
// all, unlike Team or the dead man's switch.
func (c *Client) SetEscalation(ctx context.Context, teamID int64, body SetEscalationRequest) error {
	req, err := c.newRequest(ctx, http.MethodPut, fmt.Sprintf("/api/teams/%d/escalation", teamID), body)
	if err != nil {
		return err
	}
	return c.do(req, nil)
}

// DeadmanSwitch mirrors terdut-server's deadmanSwitchStatus
// (internal/api/deadman.go), minus fields this client never reads.
type DeadmanSwitch struct {
	ID             int64  `json:"id"`
	Name           string `json:"name"`
	Matcher        string `json:"matcher"`
	TimeoutSeconds int64  `json:"timeout_seconds"`
	Severity       string `json:"severity"`
}

// ListDeadmanSwitches calls GET /api/teams/{teamID}/deadman/switches. There
// is no unique-name constraint on this resource server-side (confirmed
// against source), so this is the idempotent-create lookup for it --
// GET-list-and-match-by-name, not adopt-on-409.
func (c *Client) ListDeadmanSwitches(ctx context.Context, teamID int64) ([]DeadmanSwitch, error) {
	req, err := c.newRequest(ctx, http.MethodGet, fmt.Sprintf("/api/teams/%d/deadman/switches", teamID), nil)
	if err != nil {
		return nil, err
	}
	var switches []DeadmanSwitch
	if err := c.do(req, &switches); err != nil {
		return nil, err
	}
	return switches, nil
}

// deadmanSwitchRequest mirrors terdut-server's own deadmanSwitchRequest
// (internal/api/teams.go) -- the same body shape for both create and
// update.
type deadmanSwitchRequest struct {
	Name           string `json:"name,omitempty"`
	Matcher        string `json:"matcher"`
	TimeoutSeconds int64  `json:"timeout_seconds"`
	Severity       string `json:"severity"`
}

// CreateDeadmanSwitch calls POST /api/teams/{teamID}/deadman/switches.
func (c *Client) CreateDeadmanSwitch(ctx context.Context, teamID int64, name, matcher string, timeoutSeconds int64, severity string) (*DeadmanSwitch, error) {
	req, err := c.newRequest(ctx, http.MethodPost, fmt.Sprintf("/api/teams/%d/deadman/switches", teamID),
		deadmanSwitchRequest{Name: name, Matcher: matcher, TimeoutSeconds: timeoutSeconds, Severity: severity})
	if err != nil {
		return nil, err
	}
	var sw DeadmanSwitch
	if err := c.do(req, &sw); err != nil {
		return nil, err
	}
	return &sw, nil
}

// UpdateDeadmanSwitch calls PUT /api/teams/{teamID}/deadman/switches/{switchID}
// -- real update-in-place, added in terdut-server v0.33.0 specifically for
// this controller (that handler's own doc comment names terdut-operator).
func (c *Client) UpdateDeadmanSwitch(ctx context.Context, teamID, switchID int64, name, matcher string, timeoutSeconds int64, severity string) error {
	req, err := c.newRequest(ctx, http.MethodPut,
		fmt.Sprintf("/api/teams/%d/deadman/switches/%d", teamID, switchID),
		deadmanSwitchRequest{Name: name, Matcher: matcher, TimeoutSeconds: timeoutSeconds, Severity: severity})
	if err != nil {
		return err
	}
	return c.do(req, nil)
}

// DeleteDeadmanSwitch calls DELETE /api/teams/{teamID}/deadman/switches/{switchID}.
func (c *Client) DeleteDeadmanSwitch(ctx context.Context, teamID, switchID int64) error {
	req, err := c.newRequest(ctx, http.MethodDelete,
		fmt.Sprintf("/api/teams/%d/deadman/switches/%d", teamID, switchID), nil)
	if err != nil {
		return err
	}
	return ignoreNotFound(c.do(req, nil))
}

// Integration mirrors terdut-server's models.Integration, minus
// CreatedAt/LastUsedAt, which this client never reads. Key/URL are only
// ever populated by CreateIntegration's own response -- the one moment
// either value exists outside terdut-server's own database (DESIGN.md
// §4.5: shown once, never re-readable, same handling as the bootstrap
// admin key).
type Integration struct {
	ID     int64  `json:"id"`
	TeamID int64  `json:"team_id"`
	Kind   string `json:"kind"`
	Name   string `json:"name"`
	Key    string `json:"key,omitempty"`
	URL    string `json:"url,omitempty"`
}

// CreateIntegration calls POST /api/teams/{teamID}/integrations --
// owner-gated (requireTeamOwner), so c must hold this team's own
// team-scoped credential. No conflict handling exists server-side at all
// for this resource (no unique constraint on name, confirmed against
// source) -- deliberately not treated as this resource's idempotent-create
// recovery path; see the controller's own reasoning for why a crash
// between this call succeeding and the webhook Secret being written can't
// be recovered by listing and adopting a same-named row the way
// TerdutDeadmanSwitch does.
func (c *Client) CreateIntegration(ctx context.Context, teamID int64, name, kind string) (*Integration, error) {
	req, err := c.newRequest(ctx, http.MethodPost, fmt.Sprintf("/api/teams/%d/integrations", teamID),
		map[string]string{fieldName: name, fieldKind: kind})
	if err != nil {
		return nil, err
	}
	var integ Integration
	if err := c.do(req, &integ); err != nil {
		return nil, err
	}
	return &integ, nil
}

// RenameIntegration calls PATCH /api/teams/{teamID}/integrations/{integrationID}
// -- owner-gated, same credential requirement as CreateIntegration. Never
// touches the key (terdut-server's own handler comment: "the key is
// untouched, so nothing posting with it notices"), so this is safe to call
// every reconcile unconditionally rather than only on detected drift --
// the same "cheap, so just always sync it" reasoning TerdutEscalationRule's
// whole-policy PUT uses.
func (c *Client) RenameIntegration(ctx context.Context, teamID, integrationID int64, name string) error {
	req, err := c.newRequest(ctx, http.MethodPatch,
		fmt.Sprintf("/api/teams/%d/integrations/%d", teamID, integrationID),
		map[string]string{fieldName: name})
	if err != nil {
		return err
	}
	return c.do(req, nil)
}

// DeleteIntegration calls DELETE /api/teams/{teamID}/integrations/{integrationID}
// -- owner-gated, same credential requirement as CreateIntegration. Used
// both by the finalizer and by the kind-change rotation path (DESIGN.md §5).
func (c *Client) DeleteIntegration(ctx context.Context, teamID, integrationID int64) error {
	req, err := c.newRequest(ctx, http.MethodDelete,
		fmt.Sprintf("/api/teams/%d/integrations/%d", teamID, integrationID), nil)
	if err != nil {
		return err
	}
	return ignoreNotFound(c.do(req, nil))
}