package tools

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

	"git.d-ma.be/mathias/gitea-mcp/internal/allowlist"
	"git.d-ma.be/mathias/gitea-mcp/internal/gitea"
	"git.d-ma.be/mathias/gitea-mcp/internal/registry"
)

// dispatchResolveBudget bounds how many times we poll for the dispatched run to
// appear, and dispatchResolvePoll is the gap between polls. Gitea returns 204
// with no run ID, so we list workflow_dispatch runs and take the newest above
// the pre-dispatch baseline; it may register a beat after the 204.
const (
	dispatchResolveBudget = 5
	dispatchResolvePoll   = time.Second
)

// WorkflowRunTrigger triggers a Gitea Actions workflow_dispatch run.
type WorkflowRunTrigger struct {
	c       *gitea.Client
	a       *allowlist.Allowlist
	baseURL string
}

func NewWorkflowRunTrigger(c *gitea.Client, a *allowlist.Allowlist, baseURL string) *WorkflowRunTrigger {
	return &WorkflowRunTrigger{c: c, a: a, baseURL: baseURL}
}

func (t *WorkflowRunTrigger) Descriptor() registry.ToolDescriptor {
	return registry.ToolDescriptor{
		Name:        "workflow_run_trigger",
		Description: "Trigger a Gitea Actions workflow_dispatch run.",
		InputSchema: json.RawMessage(`{
			"type":"object",
			"properties":{
				"owner":{"type":"string"},
				"repo":{"type":"string"},
				"workflow":{"type":"string"},
				"ref":{"type":"string"},
				"inputs":{"type":"object"}
			},
			"required":["owner","repo","workflow"]
		}`),
	}
}

type workflowRunTriggerArgs struct {
	Owner    string         `json:"owner"`
	Repo     string         `json:"repo"`
	Workflow string         `json:"workflow"`
	Ref      string         `json:"ref"`
	Inputs   map[string]any `json:"inputs"`
}

func (t *WorkflowRunTrigger) Call(ctx context.Context, raw json.RawMessage) (json.RawMessage, error) {
	var args workflowRunTriggerArgs
	if err := parseArgs(raw, &args); err != nil {
		return nil, err
	}
	if err := t.a.Check(ctx, args.Owner); err != nil {
		return nil, err
	}
	if args.Workflow == "" {
		return nil, fmt.Errorf("workflow is required: %w", gitea.ErrValidation)
	}

	ref := args.Ref
	if ref == "" {
		var err error
		ref, err = t.c.DefaultBranch(ctx, args.Owner, args.Repo)
		if err != nil {
			return nil, err
		}
	}

	// Snapshot the newest existing workflow_dispatch run BEFORE dispatching, so we
	// can tell our fresh run apart from a prior one (Gitea's 204 carries no run ID).
	baseline := t.newestDispatchRunID(ctx, args.Owner, args.Repo, args.Workflow, ref)

	if err := t.c.DispatchWorkflow(ctx, args.Owner, args.Repo, args.Workflow, gitea.DispatchWorkflowArgs{
		Ref:    ref,
		Inputs: args.Inputs,
	}); err != nil {
		return nil, err
	}

	// Resolve the new run by listing workflow_dispatch runs and taking the newest
	// one whose ID exceeds the baseline. Poll briefly: the run can register a beat
	// after the 204.
	var run *gitea.WorkflowRun
	for i := 0; i < dispatchResolveBudget; i++ {
		if i > 0 {
			select {
			case <-ctx.Done():
				return nil, ctx.Err()
			case <-time.After(dispatchResolvePoll):
			}
		}
		if r := t.newestDispatchRun(ctx, args.Owner, args.Repo, args.Workflow, ref); r != nil && r.ID > baseline {
			run = r
			break
		}
	}

	// Dispatch succeeded (204). If the run has not surfaced yet, say so honestly
	// rather than failing — the workflow IS firing; the caller can list runs.
	if run == nil {
		return textOK(map[string]any{
			"dispatched": true,
			"note": "dispatch accepted but the run did not register within the resolve window; " +
				"list recent workflow_dispatch runs to find it",
		})
	}

	htmlURL := run.HTMLURL
	if htmlURL == "" {
		htmlURL = fmt.Sprintf("%s/%s/%s/actions/runs/%d", t.baseURL, args.Owner, args.Repo, run.ID)
	}
	return textOK(map[string]any{
		"dispatched": true,
		"run_id":     run.ID,
		"html_url":   htmlURL,
	})
}

// newestDispatchRun returns the most recent workflow_dispatch run for the given
// workflow and ref, or nil if none / on listing error (best-effort resolution).
func (t *WorkflowRunTrigger) newestDispatchRun(ctx context.Context, owner, name, workflow, ref string) *gitea.WorkflowRun {
	resp, err := t.c.ListWorkflowRuns(ctx, owner, name, gitea.ListWorkflowRunsArgs{
		Event:    "workflow_dispatch",
		Workflow: workflow,
		Branch:   ref,
		Limit:    20,
	})
	if err != nil || resp == nil {
		return nil
	}
	var newest *gitea.WorkflowRun
	for i := range resp.WorkflowRuns {
		r := &resp.WorkflowRuns[i]
		if newest == nil || r.ID > newest.ID {
			newest = r
		}
	}
	return newest
}

// newestDispatchRunID is newestDispatchRun's ID, or 0 if none.
func (t *WorkflowRunTrigger) newestDispatchRunID(ctx context.Context, owner, name, workflow, ref string) int64 {
	if r := t.newestDispatchRun(ctx, owner, name, workflow, ref); r != nil {
		return r.ID
	}
	return 0
}